How to reproduce:
1. Create a new project
2. Navigate to C:\Users\username\AppData\Roaming\Unity\Editor-5.x\Preferences\Layouts\default
3. Put the “UIBuilderLayoutIssue.wlt“ in the directory
4. Open the new project and change the Layout to UIBuilderLayoutIssue

Expected result: The Editor layout changes and UI Builder is seen
Actual result: Editor freezes

Reproducible with: 2022.2.0a9, 2022.3.9f1, 2023.1.9f1, 2023.1.13f1, 2023.2.0b9, 2023.3.0a5
Not reproducible with: 2021.3.30f1, 2022.2.0a8, 2023.1.8f1

Reproducible on: Windows 10
Not reproducible on: No other environment tested

Note:

• To reproduce the issue a second time, make sure to delete the UnityDefaultRuntimeTheme.tss file from the Assets folder before opening the project.
• In 2022.2.0a9 there is a “Failed to load window layout“ popup