Am I doing something wrong?
1) I created a sphere with a v-ray applied shader and just a dome light.
2) I export just the sphere using the <File <Export Selection ---->USD with V-Ray materials Exporter- selected
3) I re-import the USD using < Create <Universal Scene Description (USD) < Stage From File.
The sphere LOADS ok, but does not show up in the render itself. The sphere is invisible in the vfb.
Seems to be working fine on my end. I presume you’ve deleted the original shapes, which breaks the referencing. Try saving the file prior to exporting the USD and afterward import it in a fresh scene. For more information, check this detailed guide about the USD Workflow. Also, here are the supported features when rendering USD with V-Ray.
Now is working. I deleted my preferences folder. (to get a refresh) from default.
And now is working. I probably had something inside getting conflict.