When does it usually stock? When I was on Subeta a long time ago it stocked right after the midnight reset, but have been going there and haven't seen anything yet at any time. Thanks.

It still restocks at midnight, however sometimes it's a couple of minutes afterwards (similar to how quests don't reset RIGHT at midnight but a couple of minutes after). It also sells out pretty quickly now that there are probably more users and more knowledge about the shop.