Hi Stephane,
Sorry because inconvenience.
Now google analytics update the tracking code so user have to add full code to tracking
You have to use plugin https://wordpress.org/plugins/insert-headers-and-footers/
to add full tracking code like this
<!-- Global Site Tag (gtag.js) - Google Analytics -->
<script async src="https://www.googletagmanager.com/gtag/js?id=UA-76959356-3"></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments)};
gtag('js', new Date());
gtag('config', 'UA-xxxxxxxx-x');
</script>
Best regards
Harry
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