Hierarchy V2 SubScene foldout/expand icon disappears after undoing changes to the SubScene

Steps to reproduce:

1. Create a new 3D URP project
2. Make sure "Use new Hierarchy window" is enabled in Preferences
3. Install the Entities package
4. In the Hierarchy, right-click > New Sub Scene > Empty Scene and save it
5. Right-click on the SubScene and select GameObject > Create Empty
6. Select the SubScene and in the Inspector modify anything (e.g. change Position value)
7. Click "Ctrl+Z" to undo
8. Observe the Hierarchy

Actual results: The SubScene's foldout/expand icon disappears from the Hierarchy and its child GameObjects are no longer visible underneath

Expected results: The SubScene's foldout icon and children should remain visible in the Hierarchy

Reproducible with versions: 6000.5.0a9, 6000.5.0b11, 6000.6.0a6

Not reproducible with versions: 6000.5.0a8

Tested on (OS): Windows 11

Notes:

• The foldout icon gets restored when resetting Editor Layout or entering Play mode
• In 6000.5.0a9, right-clicking on SubScene does not work therefore you have to open the scene directly and add GameObjects or upgrade project from earlier version