Have you recently changed your site from HTTP to HTTPS? This can affect referral traffic data. You may have noticed this on your other sites’ analytics. Sami has the details and a fix.
“Normally when a visitor goes from one site to another via a link, they are logged as referral traffic and you can see the site/link from which they came within your analytics. But if they come from a secure HTTPS site to your site (which is HTTP) the referrer data will not be sent and you won’t be able to see where the traffic is coming from.
A meta referrer tag on the originating site (the HTTPS one) is one way of solving this issue.
The meta referrer tag needs to be placed in the <head> section of the HTML. It will reference one of five states and will assist in controlling how browsers send referrer information to your site. These are:
– None. No referral data will be passed.
– None when downgrade. Only send referrer info to a secure HTTPS site, but not HTTP.
– Origin only. Will send the scheme, host, and port stripped from the full URL.
– Origin when cross-origin. Will send the full URL when the target has the same scheme, host, and port, regardless of HTTP or HTTPS. Will send origin-only referral info to external sites.
– Unsafe URL. Will send the full URL as the referrer. Fragments, usernames and passwords are automatically stripped out, but other potentially sensitive info could be included, so check this first.
A more detailed spec, explanation and information on implementation can be found in the W3C working draft.”