Invoice distribution with reversal_flag='Y' but without corresponding offsetting distribution record

Hi,

We have encountered an invoice distribution that has a reversal_flag='Y' but there is no corresponding invoice distribution that offsets the amount of the invoice distribution with reversal_flag='Y'.   We're not able to recreate this situation.

This invoice distribution was matched to a PO line. While matched to the invoice, that same PO line had a "CLOSED FOR INVOICING" status. Did this PO Line status lead to the invoice distribution having reversal_flag='Y' without a corresponding offsetting invoice distribution?  If no, what could update the reversal_flag of the invoice distribution to 'Y' without creating a corresponding offsetting distribution record?