There are some reasons for this to happen. The 2 most common reasons are:
- Google search engine itself is not allowing itself to be set as the document.referrer.
- The user is moving from a secure HTTPS Google search engine page to an insecure HTTP page in your website. In such cases (moving from secure to insecure), the browser will not set document.referrer.
Whatever the reason, there's little that you can do about it.
You can consider building a solution by yourself to import Google Search Console data into Adobe Analytics, e.g. https://www.fullstackanalyst.io/blog/adobe-analytics/getting-google-search-keywords-into-adobe-analy...