Affiliate plugin - doesn't track referrals from "referrer's site"

I am using the affiliate plugin for pro sites.

Under "affiliate advanced settings" there is a place for an affiliate to place the URL where they will be sending traffic from.

However, when used this does not track clicks.

I spoke to Jose Lopes on chat about this and he confirmed that it doesn't work on your test site either. (He was going to create a ticket about this but he didn't.)