It is kind of funny. Maybe something changed since Dan’s original post introducing the temporary workaround. Or maybe it always worked this way and it just took a while for someone to
black box probe it because we aren’t given comprehensive reference documentation.
Either way, there is a 20 x 12 workaround, but it’s actually a 5:3 workaround and is only necessary in limited scenarios and will be overridden by a properly specified viewport.