So if AA is disconnected it will not fail over to a simple BT connection? On MM19 (2021 RX) if i disconnect AA, either in software or simply unplugging the phone (wired only AA connection), it will default back to BT. The BT connection does not get deleted. It will re-establish the BT connection to the multimedia system, I think, automatically.
This seems like you MM21 owners should put in a bug report (feature enhancement?) for this. Although all of my bug reports have been acknowledged and.... ignored....
Paul