Reviving Issue: UE-137684
Currently I am having this same issue that was reported in 4.26/4.27. When viewing Volumetric Clouds in VR. The clouds display over all of the foreground objects in the right eye. I am using a Vive running through SteamVR as my OpenXR runtime.
I was able to find that this problem only occurs when the r.VolumetricRenderTarget.Mode is set to 1. At 0 it works just fine, but the cloud quality is very poor for my situation, whereas 1 fixes the quality but has this bug.