Unable to add items to my shop

I opened up a shop in KMIA, and tried to add coffee to the list of items for sale. Every time I try to press “Manage supply” on the shop I get the “woah there maverick” error page. I have verified that I do indeed have coffee in KMIA and that it’s in airport storage, not airplane storage.

Update: I am able to add items to the shop mentioned above now. However I get the same issue when I open new shops. I believe this is a bug that only appears for a short time after the shop is opened, and then resolves after a few hours or days

I think I have a problem with Shops. My street vendor can sell items for the same price while the shop at the same place doesn´t.