Period End Accruals Generated Incorrectly

Hello All

We noticed that 'Period End Accruals' are genereted incorrectly during the last month end and I'm currently working through SEV1 SR (3-6526027051) . I have carried out someinvestigation to find out the root cause but couldn't succedeed hence I thought of positing my question here.

I would like to understand, At what point the PO receipt would be considered as BILLED? Because once the Invoice is Matched to PO Receipt usually we can see the QTY Billed in PO Shipments. Does the Invoice need to be validated and Paid in order to prevent the PO to be accrued when running the 'Receipt Accrual Period-End' program?