found the solution myself. if someone has the same problem, heres the solution (idk why it was unchecked ^^)
If the Rift is not working in a Packaged game, make sure that Start in VR is checked. Start In VR can be found by going to Project Settings > Description > Settings.
https://docs.unrealengine.com/portals/0/images/Platforms/Oculus/BestPractices/Rift_Packed_Game.png