If the line item "Type" in a purchase order is "G/L Account" and you post its receipt prior to receiving its invoice, you cannot post the receipt to an A/P Accrual account.

This is the three-way matching process, where the Inventory account is debited and the A/P Accrual Clearing account is credited upon posting the purchase receipt. (The A/P Accrual Clearing account is debited and A/P is credited, when the invoice is received from the vendor a few days later.)

Again, this process cannot be conducted when the line item "Type" of the Purchase Order is "G/L Account". If the "Type" is "Item", three-way matching is indeed conducted.

A future release should include this functionality.