Can't buy new item when own-limit set to 1

[Robin]

Hey

I've got MyPlaza 0.53 and the inventory module activated in MyBB 1.2.13. I created a new item with it's own name and logo, gave it a stock a 30 and an owner limit of one. Whenever someone tries to buy it they get an error message stating that they can't buy it because they already own too many of that item, even if they didn't buy anything before!

Anyone know what's going on here?