Blazor page with EditForm.OnValidSubmit dont update when calling StateHasChanged()

[Andrioden]

Describe the bug

See the complete blazor (.razor file) code below that recreates the problem as simple as possible. I want the State value to update as the HandleValidSubmit is processing, here faked by a Thread.Sleep. If you run the code and click the submit button you will see that in the browser that the value goes from 1 -> 3, and not 1 -> 2 -> (sleep 2seconds) -> 3

To Reproduce

@page "/simple"

@using System.Threading;

<EditForm Model="@Form" OnValidSubmit="@HandleValidSubmit">
    <DataAnnotationsValidator />
    <ValidationSummary />

    <div>
        <label for="name">Val</label>
        <InputText id="name" @bind-Value="Form.Val" />
    </div>

    <button type="submit">Submit</button>

    <div>@State</div>
</EditForm>

@code
{
    public class SimpleForm
    {
        public string Val;
    }

    private SimpleForm Form = new SimpleForm();

    private string State = "1";

    private void HandleValidSubmit()
    {
        State = "2";
        StateHasChanged();
        Thread.Sleep(2000);

        State = "3";
    }
}

Exceptions (if any)

None

Further technical details

• ASP.NET Core version: 3.1
• Blazor Serverside
• Visual Studio 2019, but thats not relevant

dotnet --info output

.NET Core SDK (reflecting any global.json):
 Version:   3.1.402
 Commit:    9b5de826fd

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19041
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\3.1.402\

Host (useful for support):
  Version: 3.1.8
  Commit:  9c1330dedd

.NET Core SDKs installed:
  2.1.801 [C:\Program Files\dotnet\sdk]
  2.2.401 [C:\Program Files\dotnet\sdk]
  3.1.402 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.22 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.22 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.22 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.8 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

[mkArtakMSFT]

Thanks for contacting us. Thread.Sleep results in the UI thread being blocked. Try to use the async alternative of await Task.Delay(3000). That should do it.

[ghost]

This issue has been resolved and has not had any activity for 1 day. It will be closed for housekeeping purposes.

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