If you converted a project based on the VR Template from 4.17, there was a known bug on the detection of the Oculus Rift such that the Tracking Origin was not properly set to Floor Level. That resulted in the camera being stuck on the floor.
Another possibility is that your Pawn is somehow not setup correctly or you forgot to set the Tracking Origin which, on the Rift, defaults to Eye Level.
Can you post some screenshots of your Blueprints, especially the setup of the VR Pawn?