so ive been flying my setup pretty regularly through the winter and only recently started noticing the horizon isnt sitting level like it used to. at first i thought i was imagining it but took out some footage from a few months ago and yeah theres definitely a slow roll developing on longer flights. its subtle but once you see it you cant unsee it especially on anything thats panning slowly across a landscape.

my best guess is something to do with the IMU in the gimbal getting affected by the cold? i fly around 0-5 celsius pretty often now and i never had this issue during the summer months. recalibrated twice already, once on a flat surface indoors before flying, and it helps initially but by the time im 15 minutes into a flight the drift comes back. anyone dealt with this before or know if theres a setting im missing

yeah cold weather absolutely messes with gimbal IMUs, the gyros dont like the temperature swings especially if you're going from a warm car to outside and just launching immediately. i started letting mine sit outside for like 5-10 mins before powering on and that alone cut down on the drift a lot. also worth checking if your gimbal ribbon cables have any slight tension or kink because they stiffen in cold and can pull on the roll axis more than you'd think.

the other thing i'd look at is whether the roll motor arm is fully balanced for whatever camera weight you're running. slight imbalance that gets away with it at normal temps sometimes shows up more when the motors are working harder to compensate in the cold.

dont have the exact same setup as you but had something similar last january. turned out one of the gimbal motor screws had worked itself slightly loose and i hadnt noticed. the motor was still holding but not as firmly as it should and in the cold it got worse. worth a physical check before assuming its a software or calibration thing.