I am using the Vive SDK for Unity. When I run my project, the HMD does not show the scene. It shows the default white room.
However, the view from my desktop of the game updates with the orientation and position of the vive.
Additionally, the controllers are shown as tracked and working properly on my desktop (when I angle the headset at them). Yet, as I said before, the HMD does not display the game. Only the white room.
Also, I am running Unity 5.4 beta 23. Though I have tried this on Unity 5.3 as well and it still produces the same bug.
I had this problem also. I read in another answer to make sure Direct3D11 is in the display settings in the Player → Other → Graphics APIs for Windows settings (have to turn off default of “auto” to edit). Just making sure it was there didn’t fix things for me. I ended up removing all but the 3D11 from there (and that still wasn’t enough) but then restarted the computer and the Vive and it finally worked.
Something’s a little flakey and it’s not clear what, but if you fiddle with it you can get it to work, eventually. Luck!
(I’m in 5.3.5p4; tried 5.4.xbeta 23 or something and that didn’t help).
I had this problem a couple of times.
In my case it was due to Windows 10 and administrative rights. If I ran SteamVR and Unity as administrator I never had this problem.