Currently an applied prepayment amount is not taken into account, when an imported invoice is submitted to workflow and the "Require the calculated totals to equal the imported totals for workflow submission" parameter is set to yes in accounts payable parameters (tab invoice -> invoice workflow)

For invoices an prepayment is applied to the calculated invoice amount is reduce by the prepayment amount. Based on that the calculated total differs from the imported total. For those invoices the functionality should also take the applied prepayment totals into account. Otherwise those invoices are blocked for workflow submission and the parameter must be deactivated each time to process invoices.