Reproduction steps:
1. Create a new empty project
2. Go to Preferences->General and ensure that “new Hierarchy window” is toggled on
3. In the Hierarchy, create 3-5 empty GameObjects
4. Highlight all the newly created GameObjects in the Scene
5. Press right mouse button, and then select "Create an empty parent"
6. Use the "Ctrl + Z" Keybind
7. Observe the console error
Actual result: An “InvalidOperationException: HierarchyNode(…..) not found” error is thrown in the Console after undoing the "Create an empty parent" action
Expected result: Undoing the "Create an empty parent" action should cleanly revert the hierarchy state without throwing any exceptions in the Console
Reproducible with: 6000.5.0a7, 6000.5.1f1
Not Reproducible with: 6000.0.78f1, 6000.3.18f1, 6000.5.0a6, 6000.6.0b1, 6000.7.0a1
Reproducible on: MacOS 26.5 (M1), Windows 11 (By reporter)
Not reproducible on: No other environments tested