Navio2 is not stable in stab mode

I am using a Navio2 on my quad and made a couple of flights with it only in stab mode.

The quad takes off perfectly, hovers and then after a minute, just starts to roll to the right without any RC input. I managed to save it before it crashed hard since I do the hover tests at max 1.5m.

I struggle to understand this because before this flight, I made a 38 minute hover test flight without any issues, all in stab mode. The vibes are very low, so that should not be a problem.

Attached is my logfile and mapping Roll vs. Des. Roll.

I did a second flight straight away, and the issue repeated itself, this time only seconds after take off. I am starting to lose faith in the Navio2…

Attached is the log from the first roll.

Your GPS data looks a bit weird.

I was not using GPS, only stab mode.

I suggest you also report the problem here since it might be a software issue instead of a problem with the hardware (i.e. the Navio2).