leroy1964, that happens to me too. Beside that, sometimes while hovering ~80m AGL, AP disengage like I have descended too low. Also, sometimes helicopter starts hard rotation if I forgot to reset trim before engaging hover.
I noticed that my chopper stays in (slight) permanent drop if I:
had trimmed to one side, with opposite rudder, do correction trim while still in hover, disengage hover and trim again. So, what I do? Press 'Reset trim', few times if needed.
That RCtrl+Enter is very helpful. I thought my joystick was faulty but with virtual control visible I saw that game sometimes don't register centered joystick after trim so it keeps attenuating commands.