The VR preview doesn’t work if you use it as “Play as client”.
This seems to be an engine issue because on a dedicated server the issue doesn’t happen.
I use a USB-C cable with an Oculus Quest 2.
I was able to reproduce the issue in the official unreal VR project.
Using OculusVR or OculusXR doesn’t seem to change anything.
Several other people have complained about this on different Unreal-related Discord server.