A user is able receive inventory items on a purchase order without the need to Invoice if the user chooses to.  

If the user closes a purchase order and sees the following window below

and chooses "Close Order", it will close the purchase order without posting an invoice. Spire will debit the GL account for accrued payables and credit the GL account for COGS or expense account.   

If the user did this by accident or wants an invoice to show up in accounts payable on the vendor record, the user will need to create an invoice through accounts payable and debit the GL account that was credited at the time of the closed purchase order.