OK, this will be as constructive as I can make it.
Have you looked for any anomalies with the other 13 models that are stored on the radio? Have you tried going in and reversing the aileron channel on another model selection to see if it retains that one?
Here is what I am thinking. There could be a sequence of "keystroke" or commands that when executed in a specific order cause an unexpected error. The other issue could be something like a corrupted spot in the memory. Who knows. If every other model holds changes on the radio then there is a quirk. I think the video would be helpful to see if the sequence of commands are the issue.
Stuff happens in this hobby. I am currently dealing with about a half dozen little issues with various birds in my fleet. All but two of them are directly caused by me, either from missing a detail or not catching an issue fast enough. Oh, and I walked the tail feathers of a Sukhoi into a wall by accident. The others are due to how a product was packaged causing some shipping damage (will not keep me out of the air unless I chose not to spend an extra $30 I had not planned on) and the purchase of some stock that was not of the newest variety (flashing quick connect firmware). It sucks, but it happens.
I am really sorry you lost that plane. I really am curious about my question on the other memory slots.
BTW, and I could be wrong on this. I thought the use of volatile memory requiring a battery for backup was a thing of the past. I thought we were writing to another type of memory now, more like a thumb drive. If this was a "memory battery" type issue, then at power on there would be no models stored, it would all be back to factory default.
One last thing.
PREFLIGHT!!!!
Sorry, could not resist. Hope you are in the air soon.