The stage you are submitting to has a 4 core limit, please make sure you limit to 4 cores if you want to sub to it. Or just sub without adding it to the comp.
That would be my preferred option now as well. Allowing subs with old versions would be essential imo so we don't end up with tons of unbeatable scores. And I would love to have a category that is a tad overkill for current hardware.