Unable to Access ViewData to another Action result

Hi All,

I am unable to Access ViewData["RegionData"] to another actionResult, Below is my code using ASP.NET Core 3.1 MVC

 [Route("DataUpload/[Controller]/{id}")]
        public async Task<IActionResult> Index(int id)
        {            
            IEnumerable<Entity> se;

            HttpClient client = _api.GetRegionMeter();

            HttpResponseMessage responseTask = await client.GetAsync("webscrape/" + id);


            if (responseTask.IsSuccessStatusCode)
            {
                var readTask = responseTask.Content.ReadAsAsync<IList<Entity>>();              
                readTask.Wait();
                se = readTask.Result;
                ViewData["RegionData"] = se;


            }
            else
            {
                se = Enumerable.Empty<Entity>();
                ModelState.AddModelError(string.Empty, "Error");
            }

            
        
            return View(se);


        }




        [HttpPost]
        public IActionResult Upload()
        {
            if(ViewData["RegionData"] != null)
            {
                Entity entity = (Entity)ViewData["RegionData"];
            }

            return View("Index");
        }

ViewData["RegionData"] is coming as Null

CSHTML

@using (Html.BeginForm("Upload", "RegionMeter", FormMethod.Post, new { enctype = "multipart/form-data"}))
 {<div class="row"><div class="col-6"><div class="page-title-box"><h4 class="page-title">Region Meter</h4></div></div><div class="col-6"><button id="newAlertBtn" type="submit"
                class="btn btn-success waves-effect waves-light float-right mt-3">
            Upload</button></div></div>
}

Thanks,

Shabbir