Putting ComboBox into BreadcrumbBar crashes the app

[xperiandri]

Describe the bug

      <BreadcrumbBar ItemsSource="{x:Bind ViewModel.Path, Mode=OneWay}">
        <BreadcrumbBar.Template>
          <DataTemplate x:DataType="slf:FloorItemViewModel">
            <BreadcrumbBarItem Content="{Binding}">
              <BreadcrumbBarItem.ContentTemplate>
                <DataTemplate x:DataType="slf:FloorItemViewModel">
                  <ComboBox />

Putting a ComboBox in any form crashes the app.
But if you replace UI with a ComboBox later it works

Steps to reproduce the bug

1. Create BeadcrumbBar as described above
2. Run

Expected behavior

No crash

Screenshots

No response

NuGet package version

WinUI 3 - Windows App SDK 1.6.1: 1.6.240923002

Windows version

Windows 11 (24H2): Build 26100.2033

Additional context

No response

[xperiandri]

Workaround is

<DataTemplate x:DataType="slf:FloorItemViewModel">
  <Grid>
    <i:Interaction.Behaviors>
      <ic:EventTriggerBehavior EventName="Loaded">
        <ic:ChangePropertyAction TargetObject="{Binding ElementName=FloorsSelector}" PropertyName="Visibility" Value="Visible"/>
      </ic:EventTriggerBehavior>
    </i:Interaction.Behaviors>
    <ComboBox x:Name="FloorsSelector" x:DeferLoadStrategy="Lazy"
            ItemsSource="{Binding Items}"
            IsTextSearchEnabled="True"
            PlaceholderText="Select floor"
            SelectedValuePath="Name"
            SelectedItem="{Binding SelectedItem, Mode=TwoWay}">
      <ComboBox.ItemTemplate>
        <DataTemplate x:DataType="domain:BuildingFloor">
          <TextBlock Text="{x:Bind Name}" />
        </DataTemplate>
      </ComboBox.ItemTemplate>
    </ComboBox>
  </Grid>
</DataTemplate>

x:DeferLoadStrategy="Lazy" + trigger

[evelynwu-msft]

@xperiandri Could you provide a min repro project? I tried to create one from the snippet you provided but I must've missed something because it's not crashing.

[xperiandri]

@evelynwu-msft I've tried to reproduce it on a minimal fresh project but indeed it does not reproduce.
But my app definitely crashes with it.
What else can I do?

[evelynwu-msft]

@xperiandri

1. Enable mixed-mode debugging (only necessary if it's a C# app)
2. Ensure that your debugger is configured to download symbols from the Microsoft symbol server.
3. Set a C++ function breakpoint on Microsoft.UI.Xaml.dll!OnFailureEncountered
4. Launch the app under the debugger

The callstack at the point where the breakpoint is hit should provide more information to help debug this.

[xperiandri]

It does not come to that breakpoint
This is what I see

[xperiandri]

How to get access to the source code? I loaded symbols but no source code is available

[evelynwu-msft]

Is Enable source server support checked in your debugging options?

[xperiandri]

Crash happens here
But I cannot set a breakpoint