Here is a thought. I read somewhere that some drones had a tendency to drift (left/right) when instructed to go in a straight line. Some have even attributed this to a 'poor' compass calibration/sensitivity.
It appears to me (purely guessing) that somehow DJI tried to fix that with a better (more sensitive) compass calibration. In doing so however, now the AC is more sensitive to irregularities in the surrounding magnetic field and as such, quickly determines there is an error, and switches to ATTI mode (sudden flyaway).
Now, if I have to chose between the two, I'd rather got with the small drift as opposed to sudden motions.
Better yet, is there a way to 'select' how sensitive the compass calibration needs to be performed at?
Really, the last thing one wants (and maybe this is moving that way) is to check not only the surroundings for physical obstacles, but also how smooth/rugged the magnetic field is in the area one will be flying.