In co-op, while multiple players were interacting with and viewing a merchant's offers while there were more than one item left, when one person tried to make a purchase they clicked on the item they wanted, but a different item was purchased. At first we thought it was a misclick, but this happened twice in a row. There was one item we wanted, but we ended up having to buy all three items to get it because the first two purchases bought the wrong items. It was like the selected store option index was off by one, despite closing and reopening the merchant menu. This didn't happen every time at every merchant, and I'm not sure what the repro was, but one thing we did was we had multiple people looking at the store simultaneously, and one or both of us would leave before coming back and making the purchase. It happened to both the host and client.