I've had this problem for a while now, but haven't been able to accurately capture it until now.
I often have flights where I need to give it more and more roll stick to keep it level and in one place.
In this graph of the roll variable, you can see where I initially start leaning far to the left, and then briefly land. After the next takeoff, you can see it is leaning a bit to the left, but then gets progressively more and more error to the right, and you can see me bringing it back...then the roll error starts to decrease again, to where it's staying fairly level.
I was using Alt-hold in here in some places, but other than that, a very simplistic flight.
And ZERO wind. ZERO.
Any ideas on where to start looking? Thanks.
Here is another thread you might find interesting. Any chance your APM has gotten a bit of shock damage? This is also more extreme than what you are seeing, I would guess. But also worth watching the video and cataloging the solution.