could someone try to see whether that is a general issue....
AP3825e running 10.31 (ROW)
If you cset the AP and the AP connects again to the controller the antenna selection is gone and I need to set the right antennas (and also set the radios to admin mode on) again.
In my opinion that shouldn't happen as the controller shouldn't loose that setting.
I've only tried it with a AP3825e but it could be that it's the same with other AP models with external antennas.
That happened to us as well but not consistently. 2 APs we use on a temporary basis lost their "professional installation" antenna selection. They were fine once we put the settings back in. The next time we went to use them they did not lose the configuration so we chalked it up to a fluke.