I just opened trade with Alphonse the waiter in Brimhaven, and it unlocked all the fish he has even though I didn't buy any of them. The original brozeman video's AddOn unlocks items only when entering inventory.
Can confirm. Also having the same issue.
It seems as though it's being setup to "unlock" an item on screen, rather than any item found in the players inventory.
I just opened trade with Alphonse the waiter in Brimhaven, and it unlocked all the fish he has even though I didn't buy any of them. The original brozeman video's AddOn unlocks items only when entering inventory.