Google Analytics User Explorer Doesn't Return Information for Certain Client IDs

Question

When we search for a specific Client ID (127xxxxxxx.165xxxxxxx) in the Google Analytics->Audience->User Explorer report, sometimes no data is returned for that Client ID. Why would that be?

We capture the Google Client ID when a user submits a form on our website. We then use the Google Analytics->Audience->User Explorer report to look up that Client ID's history. We have this report set to ALL USERS and we usually just search the Client ID in a date range of 2 years.

90% of the time this works. But we're noticing an anomaly where some Client IDs return no results. How can this be? If Google generates a Client ID, wouldn't this indicate that there should be some sort of information on that Client ID in our analytics report?

Answer 1

To answer this better, you have to do a lot more debugging.

Due to data sampling or internal GA4 bugs, you may not see all the data in reports, therefore, to further debug it, just export the data to BQ (or elsewhere, using the reporting API) and confirm that the export looks exactly as the user explorer (if the export contains full data, then you should just blame GA's UI or data sampling or filters, or whatever).

Now if this is the case, then maybe the problem is on-site, so you should carefully debug what is being sent and how, using debugging plugins with GTM preview making sure there are no race conditions. This kind of data debugging would be most efficient in conjunction with the BQ data exports, trying to reproduce the error where the user id suddenly changes, or hits aren't being tracked.

I think this is GA UA we're talking about here. I often use the same report in exactly the same way, searching for specific client ids to debug stuff. But we also track the client id separately in a CD since GA is not good enough to give it away as a dimension. Therefore, we can pull this data properly in custom reports by specific client id and confirm stuff.

Anyhow, what I'm saying is I've never had issues with missing GA client ids, so I would suggest starting debugging from your tracking.