My game runs in headset using Editor, but not in headset with EXE.

I am having an issue after building where my game launches on the monitor instead of the headset. It works in the editor without issue. I'm using the VRTK setup switcher, but doesn't work when I bypass that and use the SteamVR setup directly, either. It does fall back correctly, though, so the game actually runs - just not in the right display. I forced a display options dialog at the beginning, and it doesn't even offer the display as an option.

I've made sure all of the XR settings are correct, obviously, since the headset works fine in the Editor. I tried launching the exe with the -vrmode option to no avail, and even linked it to steam (as a non-steam game) with the VR options there.

I'm using Unity 2017.3.1f1, Updated SteamVR/VRTK Plugins.