Cube Orange compass off by 20-30 degrees

My Cube Orange compass seems to be off by 20-30 degrees - when compared to iphone compass or external Here3 compass heading.

For example: Cube internal compass shows 359 heading - while iphone compass shows 327 heading.

Problem is reproducible with 2 different Cube Orange boards.
Re-calibration does not seem to help.

@Alvin - any thoughts?

Can you share a picture of your setup?
Maybe some high power devices interfere the compass.

Its a Orange Cube with standard carrier - on USB power (all other electronics off) - so no interference.
Also same effect with 2 Cubes - one of them tested outside of the plane.

Can you share a disarm log?
Or you may try to turn off the compass inside Cube Orange, and use only the external compass in Here3.