Thank you for reporting a bug to Unity.
A fix for this bug has landed in Unity 6.7 and Unity 6.6. Since the fix itself is a bit involved, and the bug is contained, we've decided to skip backporting the fix to U6.5.
Steps to reproduce:
Create a new 3D URP project
Make sure "Use new Hierarchy window" is enabled in Preferences
Install the Entities package
In the Hierarchy, right-click > New Sub Scene > Empty Scene and save it
Right-click on the SubScene and select GameObject > Create Empty
Select the SubScene and in the Inspector modify anything (e.g. change Position value)
Click "Ctrl+Z" to undo
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
Prioritise and Follow this issue
Have a workaround or additional info about this issue?