It's not uncommon for a Referrer to be blank or missing on your Clicks data. There's a large number of things that can cause this to happen. We've listed some of the most common situations for why you may see “No Referrer on Clicks” below:
Direct Visit: If a user types or copies and pastes an affiliate link into their browser's address bar directly, there will be no referrer.
Private/Incognito Browsing: Some web-browsers will strip referrer information if the user is browsing in Incognito or Private mode.
Fraud Prevention enabled: If you have the Fraud Prevention add-on installed, and it's set to reject any clicks where the referrer isn't coming from one of the websites listed on the affiliate's application – https://share.cspf.co/L1urLgl6 any visit from a link published on a different website would show no referral.
HTTPS > HTTP Downgrade: Many times, the referrer will be dropped if the user clicks an HTTP affiliate link from a site that uses HTTPS. To help prevent this, make sure your WordPress site has a proper and forced HTTPS (SSL/TLS) certificate. You can work with your web host to set this up.
rel=”noreferrer”: If your affiliates add this rel tag to their links before sharing them, most browsers will strip out the referrer. You can add a policy to make this against your affiliate terms, but you'll have to be proactive in monitoring it.
Unfortunately, in most cases, there's not a lot you can do to fix this because you cannot change the way the sites your affiliates share your links on handle referrers.