All of the radio types I am familiar with feature a reset function although it is only for one airplane at a time. Sometimes the fellows will accidently activate a particular 'models' reset with a loss of all mixes and other settings but it only for that one model.

The loss of all your mixes is strange. I would start by resetting the mix on one particular model in the normal fashion and see how it goes. So yes you are likely going to need to reprogram each model that lost the mix anyway and failing this I would sent the tranny(s) in for a checkup.

John