If many affiliate clicks show as invalid with EMPTY_REFERER, check the issues below.
Reminder: Always use your Freemius r.freemius.com referral link after approval. See Affiliate program for how tracking works.
rel=“noreferrer”
WordPress can add rel="noreferrer" to links in the editor. That tells the browser not to send a referrer, so Freemius may treat the click as invalid unless your program allows empty referrers. Remove noreferrer from affiliate links:
Good: <a rel="noopener" href="//r.freemius.com/123/456/">text</a>
Bad: <a rel="noopener noreferrer" href="//r.freemius.com/123/456/">text</a>
Inconsistent protocol with default referrer policy
If the linking site has no Referrer-Policy, browsers often use no-referrer-when-downgrade. The referrer is omitted when HTTPS and HTTP are mixed. Use protocol-relative affiliate URLs:
Good: <a href="//r.freemius.com/123/456/">text</a>
Bad: <a href="https://r.freemius.com/123/456/">text</a> (can fail when the page protocol differs)
More: MDN Referrer-Policy.
