TreeViewItem does not handle IsExpanded binding correctly

[GochenRyan]

Describe the bug

After clicking the Collapse button (which sets the IsExpanded property of all bound data items to False), then clicking the Expand button (which sets the IsExpanded property of all bound data items to True), not all TreeViewItem elements fully expand.

Steps to reproduce the bug

1. Clone https://github.com/GochenRyan/WinUI3TreeViewBug
2. Checkout commit 7272036ec4013931b2a483e537b8f1bf2d952227
3. Set ExpandBug as startup project
4. Build and run

Expected behavior

All TreeViewItem elements fully expand.

Screenshots

NuGet package version

WinUI 3 - Windows App SDK 1.6.1: 1.6.240923002

Windows version

Windows Insider Build (xxxxx)

Additional context

No response

[github-actions]

Hi I'm an AI powered bot that finds similar issues based off the issue title.

Please view the issues below to see if they solve your problem, and if the issue describes your problem please consider closing this one. Thank you!

Closed similar issues:

• TreeViewItem doesn't always handle IsExpanded binding properly (#2112), similarity score: 0.84
• TreeView doesn't preserve the value of IsExpanded when containers in "content mode" are recycled and reused (#9549), similarity score: 0.81

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[GochenRyan]

I used await Task.Delay(10); to give the UI enough time to generate containers. Is there a more elegant solution?
https://github.com/GochenRyan/WinUI3TreeViewBug/commit/193ad23e2eae6a7e89a0b849bc5ef387729a03d1#diff-2c9f4b3bf90a766d4225bf2a93bfa5de5749d667e8bedd95faf2ac842d1a4fbdR104

[karkarl]

FYI, this bug seems to have persisted since WinUI2 (#2112).