I'm still a bit confused about this certain rule but I never mentioned it when it got changed in one of the earlier updates: It says (and you can save mastering those 2 decks until after your Artist Collection is approved).

That reads to me like we aren't allowed to master any deck(s) before applying for an AC card but you and Belle did master at least one deck before you applied so you didn't save it until after the AC has been approved. I'm pretty sure I've misunderstood something? Could you please clarify to me? ;;