Head movement not tracking on HP Reverb G2 Omnicept

I’m working on a VR project for the HP Reverb G2 Omnicept. I am having a problem where the game doesn’t seem to be tracking the headset movement. If I create a completely new project using the sample VR project, the headset works. However, if I open the sample VR scene in my own project, the headset doesn’t work. It seems like it must be a project setting or some other factor affecting the whole project, but I can’t find any difference between sample VR project and my own that could be causing this problem.