The quality of the compass heading data (based on LocationService.onNorthAlignedOrientationUpdate combined with GeoLocation.getNorthAlignedHeading) seems to vary quite a lot. Sometimes it's spot on, but often it's significantly off, including, but not exclusively, 180 degrees rotated. This specifically refers to the compass heading it picks up when it starts. If you start rotating your head, it looks like it's mostly IMU/SLAM tracking then, so then compass heading changes vs head rotation are quite stable. But if the initial compass heading it picked up is wrong (which happens frequently), it sticks with that misaligned heading through the rotation and doesn't correct the misalignment anymore, just nicely rotates it along.