Can't invoice received items

During an audit, I have discovered that there are many items that have been received, have not been invoiced, and do not show up to be invoiced.

I discovered this when comparing pre-payments made to a vendor against the resulting Supplier Invoices.  The Supplier is in a foreign currency, so numbers weren't lining up triggering the audit( Vendor PO in USD <> Vendor Invoice in USD -> FA Invoice in CAD <> Payment in CAD ).  Most of the differences could be accounted for due to fluctuating exchange rate.

However, we found a few invoices where the invoiced totals were significantly different ($100+).  A review of the PO against the Invoice in FA showed items not invoiced.  Going into the Supplier Invoice screen for that supplier, there are no outstanding items to invoice.  However, running

SELECT * FROM 1_purch_order_details WHERE qty_invoiced <> quantity_received;

brings up 439 rows where the qty_invoiced is 0 and quantity_received is greater than 0.

Is there a query or function to be run that will bring these missing items back into the Supplier Invoice screen?

Is there also a way to alert the person entering the invoice that items from the Receive aren't appearing on the invoice?  In this case, because of the FX and the payment made before the items being recieved into FA, it wasn't caught at the time that items were missing since a difference in totals was expected due to changing exchange rates, and therefore a close compare of the FA Invoice total against the Supplier Quoted Total wasn't done.