Passthrough over Link not working after switch to OpenXR Plug-In

I am using Unity version 2021.3.14, Oculus integration v.51 and OpenXR 1.7.0.

I was on the OculusXR Plug-In before and switched to the OpenXR-Plug-In. Before, Passthrough over Link worked, it was rendered in the classes when I activated the Playmode in Editor.

Now, it gives me this error and does not render Passthrough when I start Playmode:

"Failed to initialize Insight Passthrough. Passthrough will be unavailable. Error Failure_OperationFailed."

Also, albeit probably unrelated, I am getting this error when stopping the Playmode since I have switched to the OpenXR-Plug-In:

"InputSubsystem not found."

Please help, it is very difficult to debug Passthrough-related things if I can only see the Passthrough in builds.