I have a refund system setup so that if an item shouldnt be put back onto the inventory (damaged, past sell by date etc) i can refund it without it affecting the inventory
When refunding you are given the option to put the item back into saleable stock or damage stock, Damage stock works fine and inventory isnt affected, however when processing to saleable stock instead of INCREASING the inventory it is decreased as if im processing a sale.
Here is my action that is set to increase inventory TRUE, but this does not happen, inventory actually decreases.
i have a refund cash button and a refund card button so when an item is refunded via any of these two buttons the correct refund account (Cash or Card) is updated to show the amount of refunds processed for each
Ok then basically your returning the item with the action its adding it to inventory and then your turning right around and selling the item again (Taking it out of inventory) when you process payment aka the return payment type.
Try running the update order action on Payment Processed with that Payment Type instead.