Phantom 4 Advanced - Strange gimbal problem

[DLH_Sean]

Video is of a DJI Phantom 4 Advanced. The gimbal starts up just fine and goes to the correct placement, however within 5 seconds it will start to slowly drift downward approx 30 degrees and will not rotate back to 0 degrees. When moving the gimbal to 90 degrees it will go beyond that and then do some type of self calibration, at which point I can then move the gimbal back to 0 degrees. The camera will not hold at 0 degrees.

Any help would be greatly appreciated. I have calibrated IMU twice, gimbal calibration several times, compass calibration, refreshed the firmware, tried a different mobile device and completed the diagnostic check in DJI Assistant 2.

Thanks,
Sean
Gimbal Startup