Why is the affiliate not assigned to the buyer?

Question

1C-Bitrix

There is a partner. He gives his referral link. A person buys, registers. In the order, we see that it is from such and such an affiliate. After ordering again, we still see that it belongs to our affiliate. After the buyer deauthorizes, logs in, places an order, and we no longer see from whom he came originally. Can you please tell me what could be the problem, or is this how it should work?

Answer 1

Decided!
Installed Bitrix via bitrix_setup.php
Naively believing that it will download all the latest versions of modules. It turned out it wasn't.
Updated the online store module from version 17.8.15 to the latest one, the bug ("feature") disappeared.