JsonSerializer dont deserialize last deep of a class

Hi there I have following problem with JsonSerializer.Deserialize:

here the json string:

{"successful": true,"error": null,"content": {"pageIndex": 1,"totalPages": 32,"items": [
            {"toAddresses": [
                    {"id": 0,"name": "fidacrm@fidatek.cf","address": "fidacrm@fidatek.cf"
                    }
                ],"fromAddresses": [
                    {"id": 0,"name": "signodata gmail","address": "signodata@gmail.com"
                    }
                ],"bccAddresses": [],"ccAddresses": [],"replyTo": [],"attachments": [
                    {"id": 1,"fileName": "IMG_20170908_0001.pdf","fileNameUrl": null,"fileFullPath": null,"fileUrl": null,"contentType": {"id": 0,"format": null,"charset": null,"mediaSubtype": "pdf","mediaType": "application","mimeType": null,"name": "IMG_20170908_0001.pdf"
                        }
                    }
                ],"headers": [
                    {"id": 1,"rawField": "TUlNRS1WZXJzaW9u","headerId": 78,"field": "MIME-Version","offset": 3087,"rawValue": "IDEuMA0K","value": "1.0"
                    },
                    {"id": 32,"rawField": "RGVsaXZlcmVkLVRv","headerId": -1,"field": "Delivered-To","offset": 36,"rawValue": "IGZpZGFjcm1AZmlkYXRlay5jZg0K","value": "fidacrm@fidatek.cf"
                    },
                    {"id": 36,"rawField": "UmV0dXJuLVBhdGg=","headerId": 106,"field": "Return-Path","offset": 0,"rawValue": "IDxzaWdub2RhdGFAZ21haWwuY29tPg0K","value": "<signodata@gmail.com>"
                    },
                    {"id": 65,"rawField": "UmVjZWl2ZWQ=","headerId": 91,"field": "Received","offset": 70,"rawValue": "IGZyb20gc3Y3Ni5pZmFzdG5ldC5jb20NCglieSBzdjc2LmlmYXN0bmV0LmNvbSB3aXRoIExNVFANCglpZCBFQkNDSm4wUG4xN0QyaHNBSWNXSkVRDQoJKGVudmVsb3BlLWZyb20gPHNpZ25vZGF0YUBnbWFpbC5jb20+KQ0KCWZvciA8ZmlkYWNybUBmaWRhdGVrLmNmPjsgVHVlLCAyMSBBcHIgMjAyMCAxMToyMTozMyAtMDQwMA0K","value": "from sv76.ifastnet.com\tby sv76.ifastnet.com with LMTP\tid EBCCJn0Pn17D2hsAIcWJEQ\t(envelope-from <signodata@gmail.com>)\tfor <fidacrm@fidatek.cf>; Tue, 21 Apr 2020 11:21:33 -0400"
                    },
                    {"id": 79,"rawField": "RGVsaXZlcnktZGF0ZQ==","headerId": 47,"field": "Delivery-date","offset": 334,"rawValue": "IFR1ZSwgMjEgQXByIDIwMjAgMTE6MjE6MzMgLTA0MDANCg==","value": "Tue, 21 Apr 2020 11:21:33 -0400"
                    },
                    {"id": 94,"rawField": "UmVjZWl2ZWQ=","headerId": 91,"field": "Received","offset": 382,"rawValue": "IGZyb20gbWFpbC13bTEtZjUwLmdvb2dsZS5jb20gKFsyMDkuODUuMTI4LjUwXTozNjYyNSkNCglieSBzdjc2LmlmYXN0bmV0LmNvbSB3aXRoIGVzbXRwcyAgKFRMUzEuMikgdGxzIFRMU19FQ0RIRV9SU0FfV0lUSF9BRVNfMTI4X0dDTV9TSEEyNTYNCgkoRXhpbSA0LjkzKQ0KCShlbnZlbG9wZS1mcm9tIDxzaWdub2RhdGFAZ21haWwuY29tPikNCglpZCAxalF1aUwtMDA3ZjhHLTUwDQoJZm9yIGZpZGFjcm1AZmlkYXRlay5jZjsgVHVlLCAyMSBBcHIgMjAyMCAxMToyMTozMyAtMDQwMA0K","value": "from mail-wm1-f50.google.com ([209.85.128.50]:36625)\tby sv76.ifastnet.com with esmtps  (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256\t(Exim 4.93)\t(envelope-from <signodata@gmail.com>)\tid 1jQuiL-007f8G-50\tfor fidacrm@fidatek.cf; Tue, 21 Apr 2020 11:21:33 -0400"
                    },
                    {"id": 114,"rawField": "UmV0dXJuLXBhdGg=","headerId": 106,"field": "Return-path","offset": 265,"rawValue": "IDxzaWdub2RhdGFAZ21haWwuY29tPg0K","value": "<signodata@gmail.com>"
                    },
                    {"id": 130,"rawField": "RW52ZWxvcGUtdG8=","headerId": -1,"field": "Envelope-to","offset": 301,"rawValue": "IGZpZGFjcm1AZmlkYXRlay5jZg0K","value": "fidacrm@fidatek.cf"
                    },
                    {"id": 269,"rawField": "VG8=","headerId": 116,"field": "To","offset": 2904,"rawValue": "IDxmaWRhY3JtQGZpZGF0ZWsuY2Y+DQo=","value": "<fidacrm@fidatek.cf>"
                    },
                    {"id": 285,"rawField": "UmVmZXJlbmNlcw==","headerId": 93,"field": "References","offset": 2930,"rawValue": "IA0K","value": ""
                    },
                    {"id": 304,"rawField": "UmVjZWl2ZWQ=","headerId": 91,"field": "Received","offset": 2536,"rawValue": "IGZyb20gcGllcmNhcmxvUEMgKG5ldC0yLTQ0LTEwNy0xMi5jdXN0LnZvZGFmb25lZHNsLml0LiBbMi40NC4xMDcuMTJdKQ0KICAgICAgICBieSBzbXRwLmdtYWlsLmNvbSB3aXRoIEVTTVRQU0EgaWQgdjE5c200MjQ2ODA4d3JhLjU3LjIwMjAuMDQuMjEuMDguMjEuMDMNCiAgICAgICAgZm9yIDxmaWRhY3JtQGZpZGF0ZWsuY2Y+DQogICAgICAgICh2ZXJzaW9uPVRMUzFfMiBjaXBoZXI9RUNESEUtRUNEU0EtQUVTMTI4LUdDTS1TSEEyNTYgYml0cz0xMjgvMTI4KTsNCiAgICAgICAgVHVlLCAyMSBBcHIgMjAyMCAwODoyMTowNCAtMDcwMCAoUERUKQ0K","value": "from piercarloPC (net-2-44-107-12.cust.vodafonedsl.it. [2.44.107.12])        by smtp.gmail.com with ESMTPSA id v19sm4246808wra.57.2020.04.21.08.21.03        for <fidacrm@fidatek.cf>        (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128);        Tue, 21 Apr 2020 08:21:04 -0700 (PDT)"
                    },
                    {"id": 319,"rawField": "RnJvbQ==","headerId": 59,"field": "From","offset": 2857,"rawValue": "ICJzaWdub2RhdGEgZ21haWwiIDxzaWdub2RhdGFAZ21haWwuY29tPg0K","value": "\"signodata gmail\" <signodata@gmail.com>"
                    },
                    {"id": 320,"rawField": "WC1NYWlsZXI=","headerId": 126,"field": "X-Mailer","offset": 3193,"rawValue": "IE1pY3Jvc29mdCBPdXRsb29rIDE2LjANCg==","value": "Microsoft Outlook 16.0"
                    },
                    {"id": 334,"rawField": "SW4tUmVwbHktVG8=","headerId": 64,"field": "In-Reply-To","offset": 2944,"rawValue": "IA0K","value": ""
                    },
                    {"id": 348,"rawField": "TWVzc2FnZS1JRA==","headerId": 77,"field": "Message-ID","offset": 3030,"rawValue": "IDwwMDM5MDFkNjE3ZjAkNzhkNDdkZjAkNmE3ZDc5ZDAkQGdtYWlsLmNvbT4NCg==","value": "<003901d617f0$78d47df0$6a7d79d0$@gmail.com>"
                    },
                    {"id": 366,"rawField": "RGF0ZQ==","headerId": 44,"field": "Date","offset": 2991,"rawValue": "IFR1ZSwgMjEgQXByIDIwMjAgMTc6MjE6MDMgKzAyMDANCg==","value": "Tue, 21 Apr 2020 17:21:03 +0200"
                    },
                    {"id": 398,"rawField": "U3ViamVjdA==","headerId": 113,"field": "Subject","offset": 2959,"rawValue": "IEk6IEludmlvIGNvbiBhbGxlZ2F0bw0K","value": "I: Invio con allegato"
                    },
                    {"id": 409,"rawField": "REtJTS1TaWduYXR1cmU=","headerId": 52,"field": "DKIM-Signature","offset": 810,"rawValue": "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","value": "v=1; a=rsa-sha256; c=relaxed/relaxed;        d=gmail.com; s=20161025;        h=from:to:references:in-reply-to:subject:date:message-id:mime-version         :thread-index:content-language;        bh=Oka0/nJGKt2CJQ5m5oh0CfIAeegaI93UkR2/LZV2SHQ=;        b=KEJJl+YVI7LTIIBpxZyUvWGQHW40fSojIoB3Od8znaOFkdbrx99mppwc9akGxTMOms         Pn4bq4Ccy4yxhOEkgyemE5xVfy4GA0FAED7K/Z2qkEItzcYJmhrVwORBzIgIB5gixhn+         Qq5k+OR2vgZuX5sXG1FxBDdH4LL1Fk9/KuUeDfCQycKfu9o5ZehVQ7UYsWP+cuyhfvM0         TI2ev2HwgLQxM38+lVYBjHL5GbP5NZgQN+KrDVXbY4hjhWEcTmlEx4HOUpV3S63W+Eic         MoLMAcLrK13PfHsScjx/L86sTZbTwA1PMrFPx6ISZqvSLBNP80ZpDQlydTCgwvcNpT3C         3Dmw=="
                    },
                    {"id": 444,"rawField": "VGhyZWFkLUluZGV4","headerId": -1,"field": "Thread-Index","offset": 3227,"rawValue": "IEFkWVg2YTJVSTFMekI3eU1Rc0N4dXlnRmdZV0hJQUFBVFNZUUFBQ3RwTUFBQURwaWdBQUFlOWFBDQo=","value": "AdYX6a2UI1LzB7yMQsCxuygFgYWHIAAATSYQAACtpMAAADpigAAAe9aA"
                    },
                    {"id": 459,"rawField": "UmVjZWl2ZWQ=","headerId": 91,"field": "Received","offset": 667,"rawValue": "IGJ5IG1haWwtd20xLWY1MC5nb29nbGUuY29tIHdpdGggU01UUCBpZCB1MTI3c280MTUyNTgwd21nLjENCiAgICAgICAgZm9yIDxmaWRhY3JtQGZpZGF0ZWsuY2Y+OyBUdWUsIDIxIEFwciAyMDIwIDA4OjIxOjA3IC0wNzAwIChQRFQpDQo=","value": "by mail-wm1-f50.google.com with SMTP id u127so4152580wmg.1        for <fidacrm@fidatek.cf>; Tue, 21 Apr 2020 08:21:07 -0700 (PDT)"
                    },
                    {"id": 466,"rawField": "WC1Hb29nbGUtREtJTS1TaWduYXR1cmU=","headerId": -1,"field": "X-Google-DKIM-Signature","offset": 1489,"rawValue": "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","value": "v=1; a=rsa-sha256; c=relaxed/relaxed;        d=1e100.net; s=20161025;        h=x-gm-message-state:from:to:references:in-reply-to:subject:date         :message-id:mime-version:thread-index:content-language;        bh=Oka0/nJGKt2CJQ5m5oh0CfIAeegaI93UkR2/LZV2SHQ=;        b=qYPBqRxNS+k3rrn21cjRm9bLI9lEOdkp2NtblUHnHwHkXI7rjkbjRZLCq5Zh20Z95f         cahbTiqV4dsJFZ9VioLdMP+H6nSv3n1uXQTs/vFSNO3euwU5jjUUu1z1xF6Bu5LdpGKc         uHGoDv/KTj7ZUoCHJOCh22OPnjj2DisMz1vWOyCMF1oyWBmZ3nhXKK1PbsxNUtq8RJNN         4Y1e7e1Yabdf/L9BcpdARf6vsoAMCHizmMAPFb7IAOsJ2MCDDDLigaBQGwp3gDKHV7dT         Pfa1OIV2/AMR8i8KJUAEjjjCheQm+h2wNL+5QTpaxjH/7yxEyaOFe1h+NZGWDYiAXL9q         cCWw=="
                    },
                    {"id": 469,"rawField": "WC1Hb29nbGUtU210cC1Tb3VyY2U=","headerId": -1,"field": "X-Google-Smtp-Source","offset": 2305,"rawValue": "IEFQaVF5cEpDVDg2am1MbFJKaVNhdE0rTGU0eGg2MTkwRHh1WWI4ZGtuUlZVL0lEMkJ1SUpVL3pWWVgzY3J5VHY2QUtMWllWY2trcE5EQT09DQo=","value": "APiQypJCT86jmLlRJiSatM+Le4xh6190DxuYb8dknRVU/ID2BuIJU/zVYX3cryTv6AKLZYVckkpNDA=="
                    },
                    {"id": 485,"rawField": "WC1SZWNlaXZlZA==","headerId": -1,"field": "X-Received","offset": 2409,"rawValue": "IGJ5IDIwMDI6YTFjOjllNTE6OiB3aXRoIFNNVFAgaWQgaDc4bXI1ODYzMDIwd21lLjE3Ny4xNTg3NDgyNDY1ODc4Ow0KICAgICAgICBUdWUsIDIxIEFwciAyMDIwIDA4OjIxOjA1IC0wNzAwIChQRFQpDQo=","value": "by 2002:a1c:9e51:: with SMTP id h78mr5863020wme.177.1587482465878;        Tue, 21 Apr 2020 08:21:05 -0700 (PDT)"
                    },
                    {"id": 501,"rawField": "WC1HbS1NZXNzYWdlLVN0YXRl","headerId": -1,"field": "X-Gm-Message-State","offset": 2196,"rawValue": "IEFHaTBQdVozUGN5akx5d0Rjb2NVeXo3V09oZG5weDFFeVh4eGg1TnQ3SitITGJvdHJZRXM1TGZjDQoJYUo1VUNJbmZzdHl2dGZaZE81eGIwcC9EWXFyMg0K","value": "AGi0PuZ3PcyjLywDcocUyz7WOhdnpx1EyXxxh5Nt7J+HLbotrYEs5Lfc\taJ5UCInfstyvtfZdO5xb0p/DYqr2"
                    }
                ],"references": [],"messageFlags": [
                    {"id": 5,"messageFlag": 5
                    }
                ],"id": 15,"messageId": "003901d617f0$78d47df0$6a7d79d0$@gmail.com","uid": {"id": 15,"uidId": 32,"validity": 1567921962,"isValid": true
                },"date": "2020-04-21T17:21:03+02:00","importance": 1,"priority": 1,"subject": "I: Invio con allegato","body": "<META HTTP-EQUIV=\"Content-Type\" CONTENT=\"text/html; charset=iso-8859-1\">\r\n<html xmlns:v=\"urn:schemas-microsoft-com:vml\" xmlns:o=\"urn:schemas-microsoft-com:office:office\" xmlns:w=\"urn:schemas-microsoft-com:office:word\" xmlns:m=\"http://schemas.microsoft.com/office/2004/12/omml\" xmlns=\"http://www.w3.org/TR/REC-html40\"><head><meta name=Generator content=\"Microsoft Word 15 (filtered medium)\"><style><!--\r\n/* Font Definitions */\r\n@font-face\r\n\t{font-family:\"Cambria Math\";\r\n\tpanose-1:2 4 5 3 5 4 6 3 2 4;}\r\n@font-face\r\n\t{font-family:Calibri;\r\n\tpanose-1:2 15 5 2 2 2 4 3 2 4;}\r\n/* Style Definitions */\r\np.MsoNormal, li.MsoNormal, div.MsoNormal\r\n\t{margin:0cm;\r\n\tmargin-bottom:.0001pt;\r\n\tfont-size:11.0pt;\r\n\tfont-family:\"Calibri\",sans-serif;\r\n\tmso-fareast-language:EN-US;}\r\na:link, span.MsoHyperlink\r\n\t{mso-style-priority:99;\r\n\tcolor:blue;\r\n\ttext-decoration:underline;}\r\nspan.StileMessaggioDiPostaElettronica20\r\n\t{mso-style-type:personal-reply;\r\n\tfont-family:\"Calibri\",sans-serif;\r\n\tcolor:windowtext;}\r\n.MsoChpDefault\r\n\t{mso-style-type:export-only;\r\n\tfont-size:10.0pt;}\r\n@page WordSection1\r\n\t{size:612.0pt 792.0pt;\r\n\tmargin:70.85pt 2.0cm 2.0cm 2.0cm;}\r\ndiv.WordSection1\r\n\t{page:WordSection1;}\r\n--></style><!--[if gte mso 9]><xml>\r\n<o:shapedefaults v:ext=\"edit\" spidmax=\"1026\" />\r\n</xml><![endif]--><!--[if gte mso 9]><xml>\r\n<o:shapelayout v:ext=\"edit\">\r\n<o:idmap v:ext=\"edit\" data=\"1\" />\r\n</o:shapelayout></xml><![endif]--></head><body lang=IT link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><o:p>&nbsp;</o:p></p><p class=MsoNormal><o:p>&nbsp;</o:p></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span style='mso-fareast-language:IT'>Da:</span></b><span style='mso-fareast-language:IT'> signodata gmail &lt;signodata@gmail.com&gt; <br><b>Inviato:</b> martedì 21 aprile 2020 17:07<br><b>A:</b> 'fidacrm@fidatek.cf' &lt;fidacrm@fidatek.cf&gt;<br><b>Oggetto:</b> I: Invio con allegato<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p>&nbsp;</o:p></p><p class=MsoNormal><o:p>&nbsp;</o:p></p><p class=MsoNormal><o:p>&nbsp;</o:p></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span style='mso-fareast-language:IT'>Da:</span></b><span style='mso-fareast-language:IT'> signodata gmail &lt;<a href=\"mailto:signodata@gmail.com\">signodata@gmail.com</a>&gt; <br><b>Inviato:</b> martedì 21 aprile 2020 17:01<br><b>A:</b> 'fidacrm@fidatek.cf' &lt;<a href=\"mailto:fidacrm@fidatek.cf\">fidacrm@fidatek.cf</a>&gt;<br><b>Oggetto:</b> I: Invio con allegato<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p>&nbsp;</o:p></p><p class=MsoNormal><o:p>&nbsp;</o:p></p><p class=MsoNormal><o:p>&nbsp;</o:p></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span style='mso-fareast-language:IT'>Da:</span></b><span style='mso-fareast-language:IT'> signodata gmail &lt;<a href=\"mailto:signodata@gmail.com\">signodata@gmail.com</a>&gt; <br><b>Inviato:</b> martedì 21 aprile 2020 16:41<br><b>A:</b> 'fidacrm@fidatek.cf' &lt;<a href=\"mailto:fidacrm@fidatek.cf\">fidacrm@fidatek.cf</a>&gt;<br><b>Oggetto:</b> I: Invio con allegato<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p>&nbsp;</o:p></p><p class=MsoNormal><o:p>&nbsp;</o:p></p><p class=MsoNormal><o:p>&nbsp;</o:p></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span style='mso-fareast-language:IT'>Da:</span></b><span style='mso-fareast-language:IT'> signodata gmail &lt;<a href=\"mailto:signodata@gmail.com\">signodata@gmail.com</a>&gt; <br><b>Inviato:</b> martedì 21 aprile 2020 16:33<br><b>A:</b> 'fidacrm@fidatek.cf' &lt;<a href=\"mailto:fidacrm@fidatek.cf\">fidacrm@fidatek.cf</a>&gt;<br><b>Oggetto:</b> Invio con allegato<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p>&nbsp;</o:p></p><p class=MsoNormal>Invio con allegato in pdf.<o:p></o:p></p></div></body></html>","isHtml": true,"needReadReceipt": false,"needDeliveredReceipt": false,"inReplyTo": null,"sender": null,"messageDirection": 1
            }
        ],"hasPreviousPage": false,"hasNextPage": true
    }
}

here the code to deserialize:

            var res = await http.GetFromJsonAsync<ApiResult>("api/Email/GetUserInBoxEmails/1/Date/Desc/10/" + auth.CurrentUserId);
            if (res.Successful)
            {
                PaginatedMessages = JsonSerializer.Deserialize<PaginatedList<EmailMessageDto>>(res.Content.ToString(), options);
}

here the calss that dont deserialize:

namespace FidaBlazorUI_Share.Models.Email.ModelDto
{
    public class EmailAttachmentDto
    {
        public EmailAttachmentDto()
        {

        }
        public EmailAttachmentDto(EmailAttachment attachment)
        {
            Id = attachment.Id;
            FileName = attachment.FileName;
            FileNameUrl = attachment.FileNameUrl;
            FileFullPath = attachment.FileFullPath;
            FileUrl = attachment.FileUrl;
            ContentType = new EmailContentTypeDto(attachment.ContentType);
        }

        public int Id { get; set; }
        public string FileName { get; internal set; }
        public string FileNameUrl { get; internal set; }
        public string FileFullPath { get; internal set; }
        public string FileUrl { get; internal set; }
        public EmailContentTypeDto ContentType { get; }
    }
}

and the ContentType clas that don´t want to deserialize:

namespace FidaBlazorUI_Share.Models.Email.ModelDto
{
    public class EmailContentTypeDto
    {
        public EmailContentTypeDto()
        {

        }
        public EmailContentTypeDto(EmailContentType contentType)
        {
            Format = contentType.Format;
            Charset = contentType.Charset;
            MediaSubtype = contentType.MediaSubtype;
            MediaType = contentType.MediaType;
            MimeType = contentType.MimeType;
            Name = contentType.Name;
        }

        public int Id { get; set; }
        public string Format { get; set; }
        public string Charset { get; set; }
        public string MediaSubtype { get; set; }
        public string MediaType { get; set; }
        public string MimeType { get; }
        public string Name { get; set; }
    }
}

So the problem that on deserialization I get all deserialized except the Attachment Content Type that is sull when in the Json there is.

Thank You for help