Mademine inventory not working for Print on Demand products

[MurkwoodStudios]

Is anyone else using MadeMine for POD items? I can't get the inventory to work. It says they are out of stock. I contacted MadeMine, and they don't seem to understand the problem. They say it must be a setting on Shopify. But I can't make changes to the inventory through Shopify as it's a POD product. Is the app broken or is there a setting i'm missing. I don't seem to have any problems with other vendors.