Setting property of type System.Type in XAML doesn't set the property

I’ve validated that this works fine in OS/XAML:

Steps to reproduce the bug Latest WinUI3-preview4 (but this is not a regression from preview3, it just never worked in WinUI3)

    public class GraphPresenter : ContentPresenter
    {
        public GraphPresenter()
        {
            Loaded += GraphPresenter_Loaded;
        }

        public Type ResponseType { get; set; }

        private void GraphPresenter_Loaded(object sender, RoutedEventArgs e)
        {
            Debug.WriteLine(ResponseType); // This should have the type, but its null
        }
    }
    public class AnyClass
    {
    }

<local:GraphPresenter ResponseType="local:AnyClass"/>

Works totally fine in OS/XAML and the property is never set in WInUI3.

Expected behavior Simple C# properties of type System.Type should be populated by setting the property in Xaml.

Version Info WinUI3 Desktop app with version 3.0.0-preview4.210210.4

NuGet package version: [Microsoft.WinUI 3.0.0-preview4.210210.4]

Windows app type:

UWP	Win32
	Yes

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
October 2020 Update (19042)	Yes
May 2020 Update (19041)
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

Additional context

[RealTommyKlein]

I’ve opened a task for WinUI 3 so if the compiler encounters something like TypeProperty="local:Foo", it will generate type information for Foo so this scenario will work without a dummy class/adding the Bindable attribute.

[MikeHillberg]

Keeping this open until it’s available in a public release