Went back from SteamVR beta to normal, no change.
Error codes / warnings in log:
ERR: OpenVRDevice: OpenVR init exception.
WRN: Loading pre 17.3.0 G3D settings (0.0.0)
WRN: D3D11 Base: No DeviceContext created, not hooking device
WRN: D3D11 Base: Device creation failed: S_FALSE: 1
Like I said, Conan Exiles works, so maybe the problem is in the Rise of the Tomb Raider game itself?