I have been going through a few tutorial videos and have been practicing on the flight sim feature on the Phantom 3 Adv, however my Gimball Camera keeps sticking, it rotats to look down very smoothly but trying to bring it back to look horizontal it sticks and the just flicks round, not a smooth operation.  Is this normal?

Video:
https://youtu.be/ETJD8Tv-BdQ

No. It should be smooth up and down.

Recalibrate it in GO app.

Had that happen for the first time after doing the last update and IMU calibration.  I redid the calibration, including gimbal calibration after a cold boot of everything, and it was fine again.