How to reproduce:
1. Open the “AppUI“ project
2. Open the “SampleScene“
3. Enter the Play Mode
4. Click on the “@AppUI:selectedItemsMessage“ dropdown and select the first item

Expected result: Unity editor is responsive
Actual result: Unity Editor un-responsive

Reproducible with: 1.1.0, 2.0.0-pre.4, 2.0.0-pre.9 (6000.0.19f1)
Could not test with: 1.1.0, 2.0.0-pre.4, 2.0.0-pre.9 (2021.3.43f1, 2022.3.46f1) (“UnityEngine.UIElements“ functionality not present)

Reproducible on: macOS 14.6.1 (Intel), Windows 10 (User’s)
Not reproducible on: No other environments tested

Note:
- If errors appear when upgrading or downgrading the App UI package, close the project, remove the library folder and reopen
- Only reproducible with BindingMode set to TwoWay and ToSource