I loaded 3.0 into my Udrones Hexa-C and did compassmot- 88% interference. I did a test flight, and I saw curvey paths in auto with big variations in flight speed. I saw the red line on the telemetry listing to one side, so I decided I needed a lower interference. I installed an external magnetometer and got my interference down to 17 percent.
So now I've done a second, identical test flight, and had much the same problem. Tracks still curve, speed still fluctuates, and compass still lists. Is it my PIDs? I never had this problem before, I always adjusted crosstrack and tilt value to deal with it.