This happens a lot with my IRIS, especially on windy days!
Just upgraded today to the latest beta FW, calibrated compass and acc, result the same.
Remote mid point etc are also good.
I looked at the logs myself, saw the EKF errors, not sure related but can an expert please take a look at my logs and tell me why IRIS is not able to hold altitude during loiter?
BTW, I use a 4S battery.
Thanks in advance.