A couple of questions:
- Does the vehicle start out wobbling, and stabilise to level once that motor’s output is decreased?
- Depth hold also stabilises to a level attitude, so this is expected if your motor’s thrust contributions are not symmetric about the vehicle’s center of mass
- Have you checked that the thruster actually works?
- When the vehicle is off/disarmed, the propeller should be able to move freely when spun by hand
- If you try actuating just that motor in the Motor Test section of BlueOS (in Vehicle Setup / PWM Outputs), does the motor spin as expected?