When receiving goods (P4312) purchase receiver table (F43121) sometimes isn't updated


We are having problems with voucher matching for certain purchase orders.

We are using the 'Receipts to Match' menu option under Voucher Entry with Match (P0411). For certain purchase orders, when we try to match, no goods received are displayed.

I have investigated the matter. It seems that when goods are received, transactions are recorded in 2 files:

F43121 - Purchase Receiver
F4111 - Item Ledger

However, I find that occasionally, there is no record of goods received in Purchase receiver table, but there is a record of a GRN in the Item Ledger. Furthermore, the purchase order table (F4311) has been updated to reflect that the goods have been received. Since Voucher Match uses the Purchase Receiver table, it is not possible to generate a payment voucher without the F43121 record.

1) Why does this problem occur? The answer will help us prevent it recurring.

2) How can we rectify -- do we simply reverse the GRN and re-receive? If so, how do we ensure that this second receiving process will not generate the same omission of records from F43121 as happened the first time?