I've been flying 2.3 today and noticed some strange behaviour in Angle mode.
Acc and Mag have both been calibrated calibrated.
I'd been tuning PIDs in Acro mode and all was going well then I flicked onto angle mode and the quad drifted to the left. You could see a clear inclination of the quad, like its definition of level wasn't the same as the rest of the world ... I tried landing and rearming while the quad was level ... this used to resolve situations like this in 2.2 but it did not improve things ... so I tried rerunning the Acc Calibration routine using EzGui on my phone ... also no improvement. So I unplugged the battery and then powered it back up being careful that the quad was level and I didn't jostle it while plugging back in. Hey presto, proper level flight.
Then I swapped out to a new battery and I'm not exactly sure if I just went straight to Angle or not but I do remember when I did go to angle it also drifted off to the left ... so again I did the power cycle and again it flew level afterwards.
Not sure what is going on ... any thoughts on where to start ?