If you’re using 4.11.1 it requires Oculus SDK 1.3 so you will need to install Oculus Home to use VR preview (Setup Your Oculus: Quest, Quest 2, Link, Rift S & Rift | Oculus - 844MB downloaded during install. Unreal editor will need to restart if you are switching runtimes). FYI DK2 is fully compatible with Oculus Home despite the warning message in-app, but if you want to use oculus share demos still, you will have to set up runtime switching (use google).
I don’t know why it wasn’t working with previous versions of UE4/OVR, but if updating the runtime doesn’t help, maybe it’s a permissions issue? To be safe, make sure the editor is launched after you plug in and turn on the HMD.