Has the autotune procedure changed in 4.x?
In 3.x you hover in poshold, flip the autotune switch high to activate AT. Once it was successful you flipped it low then high to try the new settings. Land and then disarm to save.
Now in 4.x after autotune finishes and you flip the switch low then high it starts AT all over again.
If you land and disarm it does save the successful AT settings however