Controller freezes after motor start if compass enabled

If I disable the compass in MP, everything works ok.
If I enable the compass, the controller freezes as soon
as I start the motor (blades removed).
It’a GY-271 (HMC 5883L) connected to DA2, CL2.

See also Traditional Helicopter Thread

Thunder Tiger Raptor E550
Matek F405-Wing
ArduCopter-Heli 3.6.9

This also happens if the compass isn’t connected at all.