Do you run the balance check before using the gimbal?
Do you also run the autotune?
Which lens are you using with your Blackmagic 6k pro? The camera has a weight of almost 3 pounds or 1.28 kilograms and the Moza Air 2 can handle up to 9.25lbs. or 4.2kg. Depending on the lens you're using, the camera and lens combination should be within the weight limit. Also, if you're using a zoom lens it could be why your gimbal goes to sleep mode as zoom lenses don't work well with gimbals.
I just thought of two more possibilities-
Is your Roll motor locked?
Are you correctly balancing the Yaw motor? This one has to be done manually
I have the same problem. After the firmware update, Sleep Mode on the Air2 is now a very common occurrence.
Also ancountering sleep mode like all of a sudden. I think it is dangerous for the camera like 6K pro. There are uncontrolled movements of the gear. Please do sth about it as the collisions may damage the cameras.
Still have this issue on Moza Mini Mi