Trying to hook up HTC Vive with Unreal 4. When I launch UE4Editor, SteamVR says “(unresponsive) UE4Editor.exe”.
In the Editor I’m being able to launch VR Preview but glasses shows the test room only (SteamVR or Vive room, not sure) the level won’t show the viewport in glasses. On the other side, Unreal shows a preview on my monitor screen and responding to the motion.
Similar problem (was showing games on the screen, not in glasses) I had when I connected HTC Vive and my Samsung monitor together (both HDMI). I had to unplug the monitor and use DVI to make it work together.
SteamVR plugin is on (the rest as well).
I would really appreciate any ideas.
up up up up up 
please help
I am having the same issue with a new Alienware 17 laptop with a 1080 card. All other Steam apps work, but not Unreal.
I’m having the same exact problem. Legit spent hours trying to figure it out and saw this and I have an Alienware Area 51 computer. They really need to answer our questions because this is making me very frustrated.
Hi guys, i just read your posts and just wanted to say that I am using the vive and have been with Unreal Editor for the last few months with no problems but once or twice I had this issue. The only thing I could do to make it go away was a fresh restart of my PC and it would work fine again. I’m not sure if these issues are related but I thought I should mention it. Hope you get your issues fixed or sorted soon!
Hi guys i got same problem and i found solution in forums here: https://answers.unrealengine.com/questions/585278/vr-vive-ready-but-unresponsive-only-with-ue4editor.html
I just add EventBeginPlay>Execute Console Command>stereo on into BP_MotionController
Cheers
Or go into SteamVR settings and set audio to Stereo Mix.