Drifting during Manual flight after QGC shows stable level horizon


We seem to have a bit of strange behavior. We were testing indoor flight with an IRIS quadcopter with optical flow. We noticed the HUD shows drift even when the vehicle was at a stand still. After repeated calibration attempts with and without optical flow failed to fix this, we flashed the firmware. After flashing, the horizon was stable but the flight itself was not. In position hold ( with optical flow ) there was a noticeable drift. Finally, we upgraded to the V1.6.0 RC3, where we also get a stable level horizon at stand still but the manual flight is not stable. I have attached the log from the last flight. Could someone please tell us what could be the problem. Thank you.


Basic configuration

Our IRIS quadcopter with V1.6.0 RC3 and QGC v3.1.3

Your log shows that you never had any horizontal position estimation. Because of this, position control was rejected and you were still flying in manual/alt control. In these modes, positional drift is to be expected.
I would recommend that you make sure optical flow is working properly with some in-hand tests before attempting to fly with it.

Thank you for your reply. It was a faulty connection which caused the error.