Steps to reproduce:
1. Create new Unity project
2. Install Entities and Entities Graphics package via Package Manager
3. In Hierarchy create a New Sub Scene
4. Select “New Sub Scene” GO in Hierarchy window
5. In Inspector window > Sub Scene Component select “Scene Asset”
6. In “Select Scene Asset” window select “SampleScene” Scene
7. In “convert to Sub Scene” pop-up select “Convert”
8. Observe the Console window

Actual results: Converting “SampleScene” Scene to New Sub Scene throws “ArgumentException” error in the Console Window

Expected results: Converting “SampleScene” Scene to New Sub Scene doesn’t throw errors in the Console window

Reproducible with versions: 6000.3.8f1, 6000.4.0b8, 6000.5.0a6
Can’t test with versions: 6000.0.66f2 (No “New Sub Scene” GO available in Hierarchy window)

Tested on (OS): macOS Silicon Tahoe 26.2 (M1)