In 3.6.10 if you print a slip for a payment, it shows a line with the amount paid and a total of the fines/credit on the patron account. When you print a fine in 3.12.7 and supposedly master the information about the amount paid is missing and only the total is printed. May be related to the problem from bug 10027.
*** This bug has been marked as a duplicate of bug 10954 ***