GridSplitter/ContentSizer in do not work with C# Markup.

Current behavior

When I translate the ContentSizer sample in Windows Community Toolkit Gallery into C# markup, the sizer control do not show as expected. But it works with XAML.

Expected behavior

The behavior of the ContentSizer controls are the same as in the gallery。

How to reproduce it (as minimally and precisely as possible)

Create a Uno Platform App by the template in Visual Studio 2022, with: Framework: .NET 8.0 Platforms: Windows Presentation: MVUX Markup: C# Markup

Replace the MainPage.cs content with:

using CommunityToolkit.WinUI.Controls;

using Uno.Extensions.Markup.Generator;

[assembly: GenerateMarkupForAssembly(typeof(ContentSizer))]

namespace UnoApp5.Presentation;

public sealed partial class MainPage : Page
{
    public MainPage()
    {
        _ = this.DataContext<BindableMainModel>((page, vm) => page
            .NavigationCacheMode(NavigationCacheMode.Required)
            .Background(ThemeResource.Get<Brush>("ApplicationPageBackgroundThemeBrush"))
            .Content(
                new Grid()
                    .MinWidth(400)
                    .MinHeight(300)
                    .ColumnDefinitions(
                        new ColumnDefinition().Width(GridLength.Auto),
                        new ColumnDefinition().Width(GridLength.Auto),
                        new ColumnDefinition())
                    .Children(
                        // Left-side 'Shelf', In this case you could also use a GridSplitter
                        new Border()
                            .Name(out var SideContent)
                            .MinWidth(200)
                            .MinHeight(600)
                            .Background(ThemeResource.Get<Brush>("AccentFillColorDefaultBrush"))
                            .Child(
                            new TextBlock()
                                .HorizontalAlignment(HorizontalAlignment.Center)
                                .VerticalAlignment(VerticalAlignment.Center)
                                .Foreground(ThemeResource.Get<Brush>("TextOnAccentFillColorPrimaryBrush"))
                                .Style(ThemeResource.Get<Style>("BodyStrongTextBlockStyle"))
                                .Text("Side Content")),
                        new ContentSizer()
                            .Grid(column: 1)
                            .TargetControl(x => x.Source(nameof(SideContent)).Binding(() => SideContent)))));
    }
}

Workaround

No response

Works on UWP/WinUI

No

Environment

No response

NuGet package version(s)

Uno.Sdk: 5.2.175 CommunityToolkit.WinUI.Controls.Sizers: 8.0.240109

Affected platforms

Windows (WinAppSDK)

IDE

Visual Studio 2022

IDE version

17.10.5

Relevant plugins

No response

Anything else we need to know?

No response