I can confirm the same behavior on my system. I’m running 64-bit Windows build, 4.12.2 with an Oculus Rift CV1. I never had this problem until I installed the SteamVR tool from within Steam, and disabled “Developer -> Start SteamVR when an application starts” from the SteamVR dropdown menu. It was getting annoying having the SteamVR pop-up every time I’d execute PIE or standalone mode of UE4.
I was experiencing the 5-second black screen followed by exit. This behavior went away when I re-enabled the SteamVR auto-start, or just start SteamVR manually.