This is a continual problem.   QB's please offer some support in this area.   Multiple years with the same issue is just avoidance.    My team has discovered that this seems to happen when going in to edit a number in the transaction.   For instance on 4/10 you receive and packing list from supplier with 100 units on it for an order you placed.  So you receive 100 units again the PO.   But the next day you get an updated PL or discover that only 95 were sent (5 didnt make it to your facility), so you update the receipt to 95 units.   QB's at the PO level is going to see this as 95 units received twice on 4/10.  In the audit trail you will see this, at a financial level it shows as one transaction of 95 units but at the PO level your PO would be closed and you will not be able to receive the 5 units when it actually does come in.