Inventory item showing negative qty on PO even though POs are all delivered in full and closed

I have a product that is showing -42 as qty on PO, even though there are no POs open for that product.

Product history is:

Opening Qty = 0

PO raised for qty of 42

PO converted to bill for full qty so the 42 showing as Qty on PO moved to Qty on Hand

We then sold the 42 to a customer so the Qty on Hand is 0, and the Qty on PO should also be 0.

Instead it is showing -42 as Qty on PO.

I have had a chat with a customer support agent who could not assist.

Hoping to get some insight here from the community.