There are certainly some circumstances in which affiliate revenue might not be attributed. See below:
- If someone clicks another person's affiliate link in between clicking yours and completing the purchase/checking out (this even includes search engine ads, links through ads/social media/newsletters, etc.)
- If someone were to change devices in the midst of a purchase (i.e. to switch from phone to computer)
- If a different individual's coupon code is used amidst a purchase using your affiliate link
- If someone uses a coupon browser extension like Honey (or even have it installed) or if they have Rakuten installed
There are also some cases in which the merchant or retailer itself may cancel orders. Some examples may include:
- If the payment authorization has failed
- If the order was returned, canceled, exchanged, etc.
- If the sale was deemed fraudulent or was a duplicate order
As a note, these are just a handful of examples of circumstances; these may vary by retailer/merchant.