No, I had this copter flying well on 3.3 but we have it fitted with an RTK multi frequency GPS and I have been chasing problems with the SBF GPS implementation for a while so have had to keep upgrading.
There is a compass problem in here somewhere!
Last test flight with 'Learn offsets' turned on, the toilet bowling started and then it settled down until it stopped completely.
Loiter looked good, holding a tight position.
Push forward on the stick and the copter moved forward, PLUS 30deg to the left.
Same with all stick movement, 30deg divergence.
Was also getting multiple switches between mags which was causing a yaw twitch.
Obviously I have one of the 2 external mags misaligned.