No visual feedback or "Open in Prefab Mode" prompt when reordering a Prefab instance's original child GameObjects

Steps to reproduce:

1. Create a new Universal 3D project via Unity Hub
2. Create a Prefab with at least two child GameObjects (empty GameObject with two child empties, dragged into the Project window to make a Prefab)
3. Drag an instance of the Prefab into the scene (Hierarchy)
4. Expand the instance and try to drag one original child up/down to reorder it among its siblings

Actual results: The drag shows no drop/insert indicators and silently does nothing - no prompt or feedback that reordering original prefab children requires Prefab Mode.

Expected results: An unsupported reorder gives feedback - drag indicators and the "open in Prefab Mode" prompt - instead of silently failing.

Reproducible with versions: 6000.6.0b1, 6000.6.0b4, 6000.7.0a2

Not reproducible with versions: 6000.0.79f1, 6000.3.20f1, 6000.5.4f1, 6000.6.0a7

Tested on (OS): Windows 11