Marketpress allowing customers to purchase more than inventory

Hi there,

Marketpress is allowing customers to purchase more items than there are available.

https://www.dropbox.com/s/js8iqsxikbh9co3/Screenshot%202017-03-28%2022.05.11.png?dl=0

You can see in the screenshot that I only have 4 items available but Marketpress allows someone to purchase 50 items.

Please help. My customer is furious.