To recreate: 1 - Add a manual credit to a patron 2 - Create a manual invoice for any amount that is less than the account credit. 3 - Click "Save and pay" 4 - On the payment screen, click "Confirm" 5 - You're redirected to the "Make a payment screen, along with the "You must pay a value..." error message. 6 - Check the Transactions, and you will see that the fine has no amount outstanding, but there is no payment