Unit Price Doesn't Update when Quantity and Merchandise Amt are Populated

We are in the process of implementing the eSettlements module and during various testing we found if the supplier is creating an invoice line on the self service invoice and populates the quantity and merchandise amt fields, but leaves the unit price field blank the system does not automatically calculate the unit price. The system allows the invoice to be saved for later as well as submitted with the Unit Price blank. It seems that either it should calculate the value or give an error when saving or submitting. Is this functioning as designed or is it a bug?

Navigation: Main Menu > Supplier > Supplier Portal Configuration > My Invoices and Payments > Self-Service Invoice; Select Create Invoice link.