Microsoft Entity Framework Core [10100]

I have this form and when I try to submit the form, my DB gets a register with null fields, every field that supposed to fill in the form, I sent null, but the fields I've preset the value reaches the database.

This is my edit form:

<EditForm Model="@Registros" OnValidSubmit="@HandleValidSubmit" FormName="RegistrosForm">
    <DataAnnotationsValidator />
    <ValidationSummary />

    <table class="table">
        <tr>
            <th><strong>No.</strong></th>
            <th><strong>Cliente</strong></th>
            <th><strong>Asunto</strong></th>
            <th><strong>Resumen del reporte</strong></th>
            <th><strong>Describa con más detalle el registro</strong></th>
            <th><strong>Fecha</strong></th>
            <th><strong>Estado</strong></th>
        </tr>
        <tr>
            <td>@ContadorId</td>
            <td>
                <InputSelect id="Cliente" class="form-control" @bind-Value="Registros.Cliente">
                    <option value="">Seleccione una opcion</option>
                    @foreach (var cliente in Clientes)
                    {
                        <option value="@cliente.Nombre">@cliente.Nombre</option>
                    }
                </InputSelect>
            </td>
            <td>
                <InputSelect id="Asunto" class="form-control" @bind-Value="Registros.Asunto">
                    <option value="">Seleccione una opcion</option>
                    @foreach (var asunto in Asuntos)
                    {
                        <option value="@asunto.Asuntos">@asunto.Asuntos</option>
                    }
                </InputSelect>
            </td>
            <td>
                <InputText id="Resumen" class="form-control" @bind-Value="Registros.DescCorta" />
            </td>
            <td>
                <InputText id="Descripcion" class="form-control" @bind-Value="Registros.Descripcion" />
            </td>
            <td>
                <span>@Registros.Fecha.ToString("dd/MM/yyyy")</span>
            </td>
            <td>
                Nuevo
            </td>
        </tr>
    </table>

    <button type="submit" class="btn btn-primary">ACEPTAR</button>
</EditForm>

And here's my C# code:

@code {
    private Registros Registros = new Registros
        {
            Nombre = string.Empty,
            Asunto = string.Empty,
            Cliente = string.Empty,
            DescCorta = string.Empty,
            Descripcion = string.Empty
        };

    private string? UserName;
    private string? UserLastName;

    private int ContadorId;

    private List<Clientes> Clientes = new List<Clientes>();
    private List<Asunto> Asuntos = new List<Asunto>();
    private List<Registros> UserRegistros = new List<Registros>();

    private ApplicationUser? currentUser;

    protected override async Task OnInitializedAsync()
    {
        try
        {
            var authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
            var userPrincipal = authState.User;

            if (userPrincipal.Identity?.IsAuthenticated == true)
            {
                currentUser = await usermanager.GetUserAsync(userPrincipal);
                UserName = currentUser?.FirstName ?? userPrincipal.Identity.Name;
                UserLastName = currentUser?.LastName;
            }

            Registros.Fecha = DateTime.Now;
            ContadorId = IdDisplayContador();

            // Crear instancias separadas del DbContext de forma correcta
            await using var dbContext = DbContextFactory.CreateDbContext();

            Clientes = await dbContext.Clientes.ToListAsync();
            Asuntos = await dbContext.Asuntos.ToListAsync();

            UserRegistros = await dbContext.Registros
                .Where(r => r.Nombre == UserName + " " + UserLastName)
                .ToListAsync();
        }
        catch (Exception ex)
        {
            // Handle exceptions (e.g., log the error)
            Console.Error.WriteLine($"Error during initialization: {ex.Message}");
        }
    }

    private async Task LoadClientesAsync()
    {
        try
        {
            await using var dbContext = DbContextFactory.CreateDbContext();
            Clientes = await dbContext.Clientes.ToListAsync();
        }
        catch (Exception ex)
        {
            // Handle exceptions (e.g., log the error)
            Console.Error.WriteLine($"Error loading clients: {ex.Message}");
        }
    }

    private async Task LoadAsuntosAsync()
    {
        try
        {
            await using var dbContext = DbContextFactory.CreateDbContext();
            Asuntos = await dbContext.Asuntos.ToListAsync();
        }
        catch (Exception ex)
        {
            // Handle exceptions (e.g., log the error)
            Console.Error.WriteLine($"Error loading issues: {ex.Message}");
        }
    }

    private async Task HandleValidSubmit()
    {
        try
        {
            // Asegurarse de que UserName y UserLastName estén asignados
            if (string.IsNullOrEmpty(UserName) || string.IsNullOrEmpty(UserLastName))
            {
                var authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
                var userPrincipal = authState.User;

                if (userPrincipal.Identity?.IsAuthenticated == true)
                {
                    currentUser = await usermanager.GetUserAsync(userPrincipal);
                    UserName = currentUser?.FirstName ?? userPrincipal.Identity.Name;
                    UserLastName = currentUser?.LastName;
                }
            }

            //debe insertar los datos que se llenaron en el formulario
            Registros.Nombre = UserName + " " + UserLastName;
            Registros.Estado = "Nuevo";

            await using (var dbContext = DbContextFactory.CreateDbContext())
            {
                dbContext.Registros.Add(Registros);
                await dbContext.SaveChangesAsync();
            }

            // Usar un nuevo contexto para recargar los registros
            await using (var dbContext = DbContextFactory.CreateDbContext())
            {
                UserRegistros = await dbContext.Registros
                    .Where(r => r.Nombre == $"{UserName} {UserLastName}")
                    .ToListAsync();
            }
        }
        catch (Exception ex)
        {
            Console.Error.WriteLine($"Error saving record: {ex.Message}");
        }
    }

    private int IdDisplayContador()
    {
        return ++ContadorId;
    }
}

The console shows this exception:

fail: Microsoft.EntityFrameworkCore.Query[10100]

An exception occurred while iterating over the results of a query for context type 'BlazorApp1.Data.ApplicationDbContext'.

System.InvalidOperationException: A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/? linkid=2097913.

at Microsoft.EntityFrameworkCore.Infrastructure.Internal.ConcurrencyDetector.EnterCriticalSection()
at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
System.InvalidOperationException: A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.

at Microsoft.EntityFrameworkCore.Infrastructure.Internal.ConcurrencyDetector.EnterCriticalSection()
at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()

Error during initialization: A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.

I've tried to make different instances but I'm new to Blazor and I don't know if I'm doing right. I already checked the table and the model and everything looks fine.