H520E drone drifting

[polskipilot]

Hello.
What could be the reason for the drone drifting to one side (left) when it is at an altitude of over 50 m, in almost windless weather, with compass calibration performed, sticks calibrated, switched on in ANGLE mode, and yet it slowly drifts away. I have flown various Yuneec models and this has never happened in automatic mode. From I am attaching a photo of the controller.

 

[WTFDproject]

Hello.
What could be the reason for the drone drifting to one side (left) ....

Given the controller appears to be correctly calibrated, it seems at least possible the accelerometer (or maybe even gyroscope?) may have drifted a little out of calibration.
I have no experience with the H520e. Does the H520e offer an accelerometer calibration on the same screen as the compass calibration? And/or a Gyroscope?
I saw nothing in the H520e manual to describe the calibration processes. @Enrico Jorysch or others may know if the processes are the same as the earlier H520.

Update:
@Steve Carr mentioned in another venue the T3 is off center. The manual does not mention if the trim tabs were made functional for flight modes, but who knows? Again, maybe @Enrico Jorysch? Probably won't hurt anything to center it anyway.