I have a client who run Facebook Ads with UTM parameters attached to the CTA link URLs. These link to the client’s consumer site (Site A) then the user travels to the client’s online ordering platform (Site B) to complete a purchase.

Our GTM container and measurement ID are the same across both sites, and I’ve enabled cross domain tracking in the GA4 data stream settings for Site B. The problem is the final purchase event information can’t be matched up with the UTM campaign name regardless of filtering by First User Campaign or Session Campaign. I can see certain precheck out events like add to carts and item views associated with a UTM campaign name, but I can’t see anything past the begin checkout event.

Everything I’ve read indicates that if cross domain tracking is enabled, and the measurement ID is used by both sites, that I should be able to see a final dollar value associated with the UTM campaign name. I have noticed that the _glxxxxxx and subsequent cross domain info is present on the first page of Site B when a user comes from Site A, but this information disappears from the URL after the user goes to individual product pages or to the checkout page. It’s probably an obvious answer, but does the cross domain url info need to be in all page urls for cross domain tracking to work? If it does, what about Site B would be removing this from the URL?

I’ve checked the GA setup, I’ve checked the tags, I’ve made sure the measurement code is on all pages, but I still can’t figure out why I’m unable to see an association between the purchase event data and UTM campaign name.