Automatic first track selection not working after clearing and re-adding files (Skia Desktop only)

[TimGels]

Description

There is a bug affecting automatic track selection that only occurs when using the cross-platform Skia renderer desktop target. The Windows AppSDK target does not exhibit this issue.

Steps to Reproduce

1. Add a file to the application (Input tab)
2. Navigate to one of the track configuration tabs (e.g., Subtitle, Audio, or Video)
3. Return to the Input tab
4. Clear the file list
5. Add a file again
6. Navigate back to the previously visited track configuration tab

Expected Behavior

The first track should be automatically selected when navigating to the track configuration tab, as it is on first visit and as it behaves on the Windows AppSDK target.

Actual Behavior

The automatic first track selection does not occur. No track is selected in the track configuration tab.

Environment

• Affected Target: Skia Desktop Renderer (cross-platform)
• Working Target: Windows AppSDK
• Framework: .NET 10 / Uno Platform

Additional Context

The issue appears to be related to the lifecycle or state management when clearing and re-adding files, specifically in how the track ViewModels (e.g., SubtitleViewModel, AudioViewModel, VideoViewModel) handle the SelectedTrack property after the file list is modified.

The automatic selection logic in the track ViewModels sets SelectedTrack = SubtitleTracks.FirstOrDefault() in the OnBatchConfigurationSubtitleTracksChanged method, which should be triggered when tracks are updated. This works correctly on Windows AppSDK but appears to fail on Skia Desktop in this specific navigation scenario.

[TimGels]

Investigation Update

I have not found a good workaround while keeping x:Bind in place. This appears to be an issue with how Uno Platform handles binding for the Skia target.

Findings

I did notice that using {Binding} (traditional binding) instead of x:Bind does work around this issue.

Current Plan

Since Windows AppSDK is my priority target and it works correctly there, I'm not likely to convert the bindings from x:Bind to {Binding} in the near future. I may revisit this in the future if I decide to prioritize cross-platform support with the Skia renderer.

This seems to be an Uno Platform-specific issue with how x:Bind behaves on the Skia desktop target compared to the Windows AppSDK target.