I can’t rotate an xref with a clip cube, without the clip cube messing up (90 degree angles seem to work, but odd angles like 30 degree or 45 degree don’t always work well).
I would say that this is an issue that needs to be fixed -- it should work the way we expect it to. The X-Clip Cube stays orthagonal, and the X and Y extents get "twisted" to the angle. Good catch, I'd say.