When a stackable item is picked up and forced into the off-hand due to the same item already being in the off-hand, the items become stuck in the off-hand until the player is killed or dies. For example, placing a Nautilus Shell in the off-hand and gaining another one through fishing locks the items into the off-hand slot until death when they are dropped. The same occurs with arrows. When trying to remove the items through the inventory, the item doesn't let you pick it up with the cursor and using the Quick Move feature moves it properly but then puts it back in the off hand instantly.