@Hector-Gutierrez thanks for the suggestion. However, I have now seen this unstable behavior in all modes (manual, altitude, position and offboard), both indoor and outdoors. I suspect that qvio is failing and trying to reset mid flight (Error: Not stationary was observed multiple times on the qvio_overlay page on VOXL portal). I don't think the GPS is even being used (QGC reports 100 HDOP and 0 satellites). The only mode where the UAV is controllable is Manual, but the qvio error is still present.
@Alex-Kushleyev would you be able to share some insight into what could be happening? How can we resolve this issue?
Thanks,
George