Vive Pro - Unreal Engine 4.20.1 - VR Preview Greyed Out


I cannot find any solution to why VR Preview is greyed out, let alone anything recent. I know the Vive Pro is connected and working since SteamVR Home works. I have tried the following:
-Update SteamVR beta
-Disabled SteamVR Home
-Used an empty UE4 level (Blank template, Mobile, Scaling, No Starter Content)
-Also tried using Unreal Engine’s VR template
-Updated firmware on all Vive Pro hardware (Headset, Controllers, Base Stations)
-SteamVR is running before opening Unreal Engine

Computer Specs:
OS: Windows 10 64 bit
Processor: Intel(R) Core™ i7-8700K CPU @ 3.70Ghz
Ram: 16 GB

Additionally, I have tried packaging the VR Template and ran it. The headset would not rotate camera but the controllers still teleported me.
vr.bEnableStereo 1 did not do anything.