Uncommanded signal is generated

Greetings,

I conducted a test.
After takeoff, Althold Mode could not detect the instability of the Hexa Copter.
However, after changing the Loiter Mode, the Hexa Copter became unstable.
There is no Signal to the RC Input.
Whether it’s a magnetic problem or a Compass problem, the algorithm. I’d like to know about it.

2017-01-25 14-50-57.bin (1.3 MB)
2017-01-25 14-50-57.log (3.0 MB)

The multirotor needs more tuning in Stabilize. The attitude looks very sloppy, then when the loiter controller is engaged, it gets worse and out of phase. The loiter controller asks for some pitch, gets more than desired, and it oscillates back the other way setting off what you saw.

Do you mean you have to fly after tuning?
I think so too …I want to know the exact cause.
Could it be a problem for PIXHAWK?
I changed new pixhawk, and the result of the flight was stable.