"ArgumentException: WorldProxy for given world ... does not exist or is null" error is thrown when opening references in the Relationships tab of a reimported Sub Scene

Steps to reproduce:

1. Create a new URP project
2. Enable "Use new Hierarchy window" property in Preferences window
3. From the Package Manager, install the Entities package (com.unity.entities)
4. Right-click in the Hierarchy and select "New Sub Scene" > "Empty Scene..." and save the scene
5. Select the created scene and click "Close" then "Reimport" in the Inspector
6. Select the same sub scene under "Editor World" GameObject and navigate to the "Relationships" tab
7. Fully expand the "Scene System" property
8. In the "SceneReference" property click the open icon next to "Read"
9. Click on the "Relationships" tab
10. Observe the Console

Actual results: "ArgumentException: WorldProxy for given world LoadingWorld0 does not exist or is null" error is thrown

Expected results: No errors

 

Reproducible with versions: 6000.5.0b1, 6000.5.0b6, 6000.5.0b7, 6000.6.0a4

Can’t test with versions: 6000.3.14f1, 6000.4.5f1 (Editor World not available in the Hierarchy)

Tested on (OS): macOS 26.4

Notes:

• The error is thrown when clicking the "open" icon next to any property, not just "SceneReference"