CORS still blocking my web api calls - dotnet core 3.1

Hi,

CORs keeps blocking my web api calls. I have a dotnet core 3.1 web api project which I cant access at all when debugging.

My startup file looks like this 

    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }
      
        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {

            services.AddControllers();
            #region AUTHENTICATION
            services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
       .AddJwtBearer(options =>
       {
           options.TokenValidationParameters = new TokenValidationParameters
           {
               ValidateIssuer = true,
               ValidateAudience = true,
               ValidateLifetime = true,
               ValidateIssuerSigningKey = true,
               ValidIssuer = Configuration["Jwt:Issuer"],
               ValidAudience = Configuration["Jwt:Issuer"],
               IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(Configuration["Jwt:Key"]))
           };
       });

            #endregion
            services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();

            services.AddCors(options =>
            {
                options.AddPolicy("AllowOrigin",
                 builder =>
                 {
                     options.AddPolicy("AllowOrigin",
             builder => builder.WithOrigins("https://localhost:44383", "http://localhost:53711")
                               .WithMethods("GET", "POST").AllowAnyHeader());
                 });

            });
            services.AddMvc();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            app.UseHttpsRedirection();
            app.UseRouting();
            app.UseAuthentication();
            app.UseAuthorization();
            app.UseCors("AllowOrigin");
            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }

What else do I need to do to get this to work ? Any help will be much appreciated