Hm. Don’t see anything suspicious. Does it happen 100% of the time? Can you also attach the most recent (after attempting to enter VR Preview mode) ServerLog_*.txt log from \AppData\Local\Oculus? (the name will be something like ServerLog_2015-08-23_21.04.57.txt).
Also, can you try to install the 0.7 Runtime - https://developer.oculus.com/ (it has support for 0.6 apps)? The way you describe the issue leads me to thoughts that the issue is unrelated to UE and could be solved by installing new Runtime.
Sorry my post wasn’t clear, I have this problem with the 0.7 runtime as well. The only difference from the previous runtime is that it is 100% going to work if I get a black screen, launch the oculus demo thenexit it. On 0.6 that sometimes fixed the app but not often. I will post the server logs when I get home. It is possible that it is just my project so let me also try a fresh simple project. Lastly to be clear that this is always on external launch with 0.7 or 0.6 runtime but preview 100% reliable for me with 0.7 runtime if doing in editor vr preview.
The issue dealing specifically with a black screen in stand alone has not been implemented. This thread is for the issue UE-17053. The issue that you are currently describing is UE-17125. They are similar but they require different solutions. The issue UE-17125, is currently being looked into by the developers. I hope that this information helps.