I have a fly away problem in loiter, AC 3.0.1, and I've seen that there is a misleading issue with my external compass HMC5883 (3dr robotics). The arrow silkscreened shows an incorrect direction.
I don't know if that corrects my fly away problem, but the true is that I have compass_orient parameter = 0 (not correct).
I will test tomorrow.
Please, advise at wiki.
This is APM 2.5 (see compass IC code and arrow)
This is the external mag (y arrow and IC text):