[UPDATE: Turned out to be operator error - compass was installed on the wrong leg] I find GPS mode very difficult to fly - I am constantly fighting the craft. In Atti mode, it is a rock (unless the wind blows). However whenever I flip to switch to GPS, it banks. Not circular - just picks a direction and heads that way picking up speed unless I override with the stick control. Not always the same direction (so not a stick calibration issue - although I did try re-calibrating the TX). If I start in a hover in atti, then flip the switch to GPS it will hover for a few seconds, then slowly tilt one direction until it is going full tilt (literally). Almost seems like one of the feedback signals is inverted (when it detects motion north, it interprets that as south and compensates in the wrong direction). At one point, I waited too long to correct with the TX (wanted to see if it eventually changed direction) and I was unable to overpower the direction it wanted to go. I ended up having to ground it while it was still moving pretty fast as it was about to smash into my house and I didn't have time to flip back to atti. Prior to updating the firmware to 3.10, I never noticed this behavior (it was pretty solid - occasionally exhibiting a circular motion when in a light breeze). I don't dare try the RTH feature until this is resolved! Any suggestions? I guess I should mention I did do a full (long) IMU calibration, recalibrated the compass, recentered the TX, and reinstalled the firmware. Multiple times.