I was RS in a Viscount simulator when LS got us inverted at 16,000'. The white on black AH did not help.
I spent the next 16,000' telling him we were inverted.
Hearing can shut down in a high stress situation. If there's no appropriate response to two communications, it's time to announce incapacitation and take over control.
Simulator sessions need to include incapacitation scenarios and discuss the subtle cases as can and does happen with disorientation.