Actually Pixhawk1 firmware should be fine, because I just checked and it pulls in (or relies on) fmuv3 anyway. So no big deal there.
My next guess would be that your internal compass doesnt actually work properly (or at all).
A lot of those Pixhawks are very cheaply made often with “factory-seconds” parts and substitutes. Even some of the “reliability” parts get left out entirely, so they can be more prone to failure.
AND often the internal compass is too close to large current flows and never works effectively in flight anyway, so is often disabled.
Just set it to disabled, only use the external compass.
Continue the upgrade process to firmware version 4.4.3
I will do it
Thanks a lot
I also meant to point out that your compasses and IMUs are all supported by Pixhawk1 (fmuv3) firmware, so if something doesnt work it’s probably a sign of the cheap Chinese knock-off syndrome.
OK, Tanks disabling internal compass worked fine