Changing FlyoutShowMode does not take effect

[HO-COOH]

Describe the bug

Setting the ShowMode of a Flyout does not take effect. See the pull request here for an example. Even setting it manually in xaml like this

                <Button Content="Click for flyout">
                    <Button.Flyout>
                        <Flyout x:Name="CustomFlyout" ShowMode="Transient">
                            <TextBlock Text="This is a flyout"/>
                        </Flyout>
                    </Button.Flyout>
                </Button>

I would still get Standard mode when the flyout is opened, as this suggests

            <local:ControlExample.Xaml>
                <x:String xml:space="preserve">
&lt;Button Content="Click for flyout"&gt;
    &lt;Button.Flyout&gt;
        &lt;Flyout ShowMode="$(ShowMode)"&gt;
            &lt;TextBlock Text="This is a flyout" /&gt;
        &lt;/Flyout&gt;
    &lt;/Button.Flyout&gt;
&lt;/Button&gt;
                </x:String>
            </local:ControlExample.Xaml>
            <local:ControlExample.Substitutions>
                <local:ControlExampleSubstitution Key="ShowMode" Value="{x:Bind CustomFlyout.ShowMode, Mode=OneWay}"/>
            </local:ControlExample.Substitutions>
        </local:ControlExample>

Steps to reproduce the bug

See above

Expected behavior

No response

Screenshots

NuGet package version

WinUI 2 - Microsoft.UI.Xaml 2.8.1

Windows version

Windows 11 (22H2): Build 22621

Additional context

No response

[github-actions]

This issue is stale because it has been open 180 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[HO-COOH]

Still reproducible with WinUI 2.8.5 package.

[ranjeshj]

This repros in WinUI3. @HO-COOH good find.