How to reproduce:
1. Open the attached “IN-140734” project
2. In the Assets folder within the Project window open “Document”
3. Expand template instance named "#Label"
4. Select Label named "#Label"
5. Modify any attribute on the selected element
6. Observe the Console window
Actual result: A "InvalidCastException: Specified cast is not valid." error is thrown
Expected result: No errors in the console
Reproducible with: 2023.1.0a14, 6000.0.74f1, 6000.3.14f1, 6000.4.5f1, 6000.5.0b6, 6000.6.0a4
Reproducible on: Windows 11, Tahoe 26.4.1 (M1 Max)
Not reproducible on: No other environments tested