Augustus 4.0.0.21 specific items stop trading

[badgermolegit]

In both Lugdunum and Mediolanum of the most recent Reconquered Campaign, I've experienced a nearly identical bug. Randomly one specific item will stop being traded by traders despite trading being on, warehouses empty & set to receive that item. It is not due to trade limits, because I can import another item from the same city without issue. In Mediolanum it happened with wheat, and in Lungdunum it is happening with lumber.