Undo Actions are ungrouped when a custom Editor window inspecting the referenced Instance ID is open

How reproduce:
1. Open the “IDUndo.zip“ project
2. Open the 'Test Window' (BugRepo > Open Window)
3. Open the Undo History Window (Edit > Undo History, or CTRL + U)
4. Select "Assets/New Test Asset" in the Project Window
5. Select the Asset field in the Inspector window to focus on it
6. Press the “Delete” key
7. Observe the Undo History Window
8. Undo once
9. Observe the “TestWindow” window and the Inspector

Expected results: The Instance ID and the Asset reference are both restored
Actual results: Only the Instance ID is restored

Reproducible in: 2021.3.41f1, 2022.3.39f1, 6000.0.12f1

Reproduced on: Windows 11 Pro (23H2)
Not reproduced on: No other environment tested

Notes:

• When the “TestWindow“ is not opened, the Instance ID is not modified, but as soon as it is opened and an Undo is made, the Undo name changes from “Modified Asset in New Test Asset“ to “Modified Instance ID in“
• Sometimes after undoing the “Modified Instance ID in“ the action cannot be redone
• If able to redo, both actions will be redone on one call, but only one action will be undone on one undo call
• In 2021.3.41f1, the actions do not seem to be ungrouped, but when redoing the action, no action is redone in the Undo History