Unfortunately in this instance the automated checker was absolutely fine and the proof copies look lovely. However somebody manually checking decided that it didn't meet their standards that "all elements intended to be viewable appear at least 0.716in (18.175mm) away from the outside edges" despite me arguing that it wasn't intended to be viewable. As such they have a policy aimed at preventing people from doing something accidentally, but are applying it heavy handedly against somebody who is doing it deliberately.