The save file associated with the game may be corrupted. See if deleting it works. The save file is created on the first load of your main menu, and it was broken a few updates ago. The .sav should be located at C:\Users\[YOURNAME]\AppData\Roaming\UNKYS.exe iirc.
If it isn't a corrupted save file or Oculus/SteamVR interference, then I'm not sure what could be causing the issue. It makes sense that neither of those things are causing problems, as I'm sure I've integrated fail-safes for both of those things in the current build, but I haven't heard of an issue with an unwarranted black screen without any prior gameplay. I'm sorry I can't help more! Hopefully it'll fix itself with the next update.