There could be several reasons why your GTM isn’t properly linking to your new GA4 property. Firstly, you should ensure you’ve selected the correct GA4 configuration tag in your tag configurations within GTM. Double-check whether you’ve copied your GA4 measurement ID exactly as it appears on your GA4 property – any typos or extra spaces could prevent it from working. Also, ensure that the GTM container you’ve used in your GA4 measurement ID is published.
In the GTM interface, you should verify that your GA4 configuration tag is firing correctly on the pages you want it to by using the GTM Preview mode. If your tag is not firing as desired, consider checking your trigger settings. If the issue persists, there’s a chance that the data may be blocked by browser settings or extensions such as ad blockers, which can prevent GTM and GA4 from working correctly.
Disconnecting from GA3 should not necessarily impact GTM’s connection to GA4, as these are separate systems, so it’s advisable to focus more on configurations relating to GA4. Remember that changes in GA4 can take up to 24 hours to appear in the reports. If everything looks correct, patience could be the key. If all else fails, you could try enlisting the help of a digital analytics expert to look into the problem.