Disabling the sensor doesn’t sound like a good idea. The main motion tracking for the Oculus takes place inside the head-set, in its Inertial Measurement Unit, the constellation sensor just complements and corrects it. Even if you manage to disable/rotate away the sensor all you will get is a very bad tracking of the HMD with the consequent warning/error from the Oculus software.
What you would rather need to do is prevent any unwanted rotation (e.g. pitch rotation) of the HMD from being applied to your camera inside UE4. What follows is from the top of my head because I cannot test it right now.
- First uncheck the Follow HMD rotation for your VR Pawn.
- Then inside your VR Pawn Blueprint use Get Orientation and Position to get the orientation/position of the HMD.
- From it extract only the Yaw rotation and apply it to the VR Pawn camera via AddRelativeRotation. This step may be different depending on how your VR Pawn is setup.
Give it a try and see if it works. I will test it myself as soon as I have the chance.