Discount Code Usage
This report includes a list of all your discount codes along with how many times each of them was used and how much each of them discounted in total.
Troubleshooting
Discount code has a count but no discounted value
This happens when no invoice is issued with that discount.
Discount code shows 0 uses but has a discounted amount
This happens when an invoice with the code was deleted and issued again, with the same code, which resets the use count.
Invoiced Discounts
This report includes a list of all the invoices that included a discount code and how much was discounted in each of them.