Audio Position locked on App start for Fully Immersive Unity builds. No head tracked audio. Often starts hard panned to left or right

I’ve noticed that audio is locked into position with builds. It sometimes comes out the left ear, other times the right. I occasionally get it working with both, but the audio isn’t moving with head tracking.

I've seen other reports of this issue in the Unity support forums too.

Any ideas on how to fix this? Its being reported in my app reviews as a negative.