Regression: mouse wheel unusable in scrollviewer containing stackpanel in v1.6

[fredemmott]

Describe the bug

If a scrollviewer contains a stackpanel, the mouse wheel should be able to scroll it. This works in v1.5, but not v1.6

Steps to reproduce the bug

1. Install MSI from https://github.com/OpenKneeboard/OpenKneeboard/actions/runs/10832469563
2. Go to settings -> advanced
3. Try to scroll with wheel
4. Does not scroll
5. Use scrollbar, scrolls

Expected behavior

Scroll wheel should scroll.

This matches the behavior on v1.5, e.g. OpenKneeboard/OpenKneeboard@ae05366 fixes it (CI build at https://github.com/OpenKneeboard/OpenKneeboard/actions/runs/10832950077 shortly)

Screenshots

No response

NuGet package version

None

Windows version

Windows 11 (22H2): Build 22621

Additional context

XAML is here: https://github.com/OpenKneeboard/OpenKneeboard/blob/master/src/app/app-winui3/AdvancedSettingsPage.xaml