Classes must be set to allow discounts. Go to Find | Classes, search for the class that discounts aren’t working for and edit the class. Scroll down to Class Fees. If the Discount is set to False, delete that fee line item and create a new one. Enter the fee type, fee amount, select the G|L code (if applicable), tick the Discountable checkbox and click Add Fee. The Discount should now be set to True. Scroll to the bottom of the screen and click save.