If you're using Donate for Discount and suddenly you have an order where the customer chose to donate but didn't receive the donation at checkout, check whether your customer paid with PayPal. If you have third-party payment provider payment options somewhere other than checkout (i.e., at cart), the discount from the Donate for Discount campaign might not work all the time.
So you'll want to make the PayPal (or other third-party) payment option display at checkout only (not cart). This will circumvent the problem.
Reach out to us at email@example.com for additional assistance.