so ive been dealing with this for like three weeks now and its driving me insane. every time i do a full IMU and gimbal calibration the horizon looks perfect on the bench but then i get out in the field and after maybe 10-15 minutes of flying the roll axis just slowly creeps. not a lot, maybe 1-2 degrees, but enough that i notice it in post and have to correct it which is a pain when im shooting anything with a clear horizon line.

im running a custom build with the O3 air unit and a lightweight 3-axis brushless gimbal, not the stock DJI stuff. total payload is around 340g which should be well within the gimbal's rated limit. i balanced the camera as carefully as i could, checked it multiple times. the drift doesnt seem to be related to wind because it happens on calm days too. anyone dealt with something like this or have any idea what im missing here

had almost the exact same issue last year on a similar setup. turned out my gimbal motor on the roll axis was running warm, like noticeably warm to the touch after a flight, which meant it was working harder than it should've been to hold position. rebalanced everything super carefully ? and i mean obsessively carefully ? moving the camera mount forward maybe 2mm and it basically went away. even a slight forward or rearward imbalance makes the roll motor fight constantly and eventually it just loses the battle a little bit. worth checking if your motors are getting hot.

not sure if this is your problem but what firmware are you on for the gimbal controller? some of the older versions had a known issue with gyro drift compensation not working right at certain temps. also does the drift happen more when the sun's been on it for a while? asking because i saw someone mention thermal expansion in the mounting plate causing alignment issues on a carbon fiber arm build, which sounds weird but apparently it was real lol