Apparently I have the artifact treasure sets done... **bleep**. I really hope that gets sorted, treasures are something I'm pretty **bleep** about doing properly. :/
EDIT; Actually the trophy itself has unlocked, just on the in-game menu. If this stops me from actually unlocking it once treasures are patched...
Once you back out of MP and go back in everything resets to normal. It seems to only happen the 1st time you log in for the day.
Not for me, everything is still unlocked. Take that trophy people >:3