Can't get Valve Index / Steam VR to work

I’ve used my Valve Index to play WT in VR quite a bit. It’s been impossible to make it work consistently lately, and today I can’t get it to work at all.

I’ve tried deleting the cache folder on each startup, launching from launcher.exe, aces.exe, the Steam Library, and from the Steam VR interface. I’ve set config.blk to read-only with all VR options set to Yes. I’ve tried running the game with and without Steam VR running.

Nothing seems to just make it work reliably. Could anyone help troubleshoot please?