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 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.