Server-side measurement is running, but you don't see conversions in GA4. The cause is almost always in one of four points along the chain. Here's how to isolate it top to bottom.
1. Does the event reach the server-side container?
In the server-side GTM container's preview mode, walk the site and watch whether requests from the site arrive at all. If not, the problem is in the web GTM → server container link (wrong transport URL or domain).
2. Does the GA4 tag fire, with the right details?
Still in preview, check that the GA4 tag fires and has the Measurement ID and API secret filled in. A typo or swapped values is the most common reason data never arrives.
3. Does the event reach GA4?
In GA4, open DebugView and watch whether the event arrives — and with which parameters. If it arrives but value or parameters are missing, the problem is in mapping or the data layer, not the connection.
4. Is consent blocking it?
If you have Consent Mode set up and the event is only sent with consent, check that you're testing with consent granted — otherwise the GA4 tag correctly doesn't fire. That's not a bug but expected behavior.
Common specific causes
- Wrong Measurement ID or API secret.
- The event has a different name than the one GA4 responds to.
- The conversion isn't marked as a key event in GA4.
- Standard reports lag — DebugView is instant, standard reports are not.
The setup steps are in the GA4 server-side docs. For the general verification routine see how to verify server-side tracking works.