Particles don't face camera in VR only

I’m trying to fill my scene with some big fog particles that move past the camera quickly to simulate fast movement.

In the editor they show up fine, in VR they only show up on one hemisphere of my vision, which is fixed to the world.

Here’s a screenshot of the editor, showing fog everywhere:

Here’s a screenshot from VR showing the fog only visible on one hemisphere of my view:

I’ve tried toying with the PSA_blah enum in the particle editor, but it doesn’t seem to fix this. I’ve also tried making my fog material two sided, but it doesn’t help. Why is this happening?