The biggest problem is when external hardware (Honeycomb Bravo, for example) have automatic switch assignments to AVIONICS OFF and people don’t put two and two together, then complain that their airliners don’t receive any VOR/ADF/ILS signals at all because the event coming from the switch cannot be overridden (and it keeps sending the event on full repeat every cycle - what a waste of CPU ).
This caused huge headaches to the customer support team until we figured that out and told the customers.