AutoSuggestBox menu is zero-height

Describe the bug

The suggestion menu of a WinUI AutoSuggestBox appears to be near zero height, even when list of suggestions is not empty.

Steps to reproduce the bug

1. Install and open XAML Studio.
2. Copy the following XAML into the editor:

<Page
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Padding="40">
        <AutoSuggestBox>
            <x:String>Howdy</x:String>
            <x:String>Suggestion</x:String>
            <x:String>Another suggestion</x:String>
        </AutoSuggestBox>
    </Grid>
</Page>

1. Type some text into the box. Observe that a tiny sliver of the suggestions menu appears.

Expected behavior

The suggestions menu should show the current suggestions (AutoSuggestBox.Items).

Screenshots

NuGet package version

Microsoft.UI.Xaml 2.7.0

Windows app type

• UWP
• Win32

Device form factor

Desktop

Windows version

Windows 10 (20H2): Build 19042

Additional context

XAML Studio still uses WinUI 2.3, but I initially ran into this issue with an Uno UWP app using WinUI 2.7 and was able to repro with WinUI 2.8.0-prerelease.220118001.

[RealTommyKlein]

I can reproduce using the given markup.

To me it looks like AutoSuggestBox doesn’t pass Items to ListView (only passes ItemsSource), so directly add items in <AutoSuggestBox> doesn’t work.

This is what I found as well. This is unrelated to Binding/x:Bind, setting ItemsSource works but Items doesn’t. @ojhad here’s a repro in a VS project, where the project’s markup uses Items which doesn’t work, but clicking the Button sets ItemsSource in code-behind which then works: AutoSuggestBoxRepro.zip . Note that Binding/x:Bind is never used.

[yoshiask]

@ojhad I’m targeting v2004 / b19041.