Hello, i think you can reset only rotation, not only vertical.. To do that what works in my project that node Reset Orientation and Position and select Orientation. I hope it's will help you.
If you get the denial for VRC.PC.Input.3 on the vertical reset, there are two things you could do: 1) Just classify your app as a full-room / standing app and NOT a sitting app. The vertical reset is for sitting applications. 2) Or, you could modify the OVR rig to be "eye level" instead of "floor level". That should do the vertical reset automatically.