"EKF3 IMU1 MAG0 IN-FLIGHT YAW ALIGNMENT" makes auto yaw when takeoff

ArduCopter Copter 4.5
13

OK, I saw the tech-support here: EKF3 IMU0 in-flight yaw alignment complete · Issue #24823 · ArduPilot/ardupilot · GitHub

I’ll apply EK3_MAG_CAL = 4 first. BTW, copter default is 3.

And at the mean time, I will try to know more, but apparently it has something to do with AP_NavEKF3. No that simple to understand.