[Elizabeth]

From your question, it seems that you are trying to connect Google Analytics 4 (GA4) and Google Tag Manager (GTM) for cross-domain tracking and event triggering. The ‘gtag’ command you mentioned is a part of Google’s Global Site Tag (gtag.js) system, which is used to unify tracking systems across Google’s suite of tools.

To initiate GA4, you’ll need to use the ‘config’ command with your GA4 property ID. This should initialize tracking. Configuring it through GTM as well may cause duplication or override your configurations.

Instead, you can use GTM to manage the custom events you want to track. For cross-domain tracking, you need to have GA’s ‘Linker’ setting enabled on both domains, and they need to be specified in the Referral Exclusion List.

The clientID and SessionID should be automatically handled by Google Analytics. If you’re not finding them in your reports, there may be an issue with the setup.

In short, use ‘gtag(config)’ to start tracking with GA4, use GTM for custom events, and enable ‘Linker’ for cross-domain tracking. Check your setup if clientID and SessionID aren’t appearing correctly. Technical help may be needed to figure out the exact issue.

[Elizabeth]

The issue you’re encountering with GA4 is a known bug. The system is mistakenly converting your 37-digit number value into an exponential format. A simple workaround is to add a non-numeric symbol, like a dot, at the end of your number value, such as 86594184624443841463509305394505323179.

When I’m sending a Client ID to GA4 as a custom dimension, the same thing happens – it transforms it to a number. So, I just add a dot at the end and then manually remove it in the exported reports. I know it’s not ideal, but until the bug is fixed, this should allow you to view your data correctly.