I recently implemented Cross Domain tracking on 2 domains. First, I added my GTM script on the second domain (who already had another GTM script). Then, on the GTM, on the GA Pageview tag, I added the second domain to the Auto Link Domains, set the allowLinker variable to true, and set the cookieDomain to auto. Now, when I navigate from the first domain to the second domain, the _ga and _gid cookies are the same on both domains, but still I don't receive any data of my second domain on Analytics 360. Where did I go wrong?
For a timely resolution, reach out to the 360 support rep for the account.. it's included in the 360 price tag!– Bronwyn VDec 2, 2021 at 1:04
You have to use GTM preview on the second domain and properly debug your tags. It looks like your problem has no relation to the auto-linker.
Make sure that your tags are firing with no issues and that they have the correct property id set. Then you also may debug it through the Network tab, comparing the request between two domains. And, surely, you can look at the real time data.
Don't forget that you're not getting your data immediately. Wait for two days.