I had GA configured via the Soil module since my site launched prior to the sunsetting of Universal Analytics this past June. But no data has been collected since then, because Soil was never patched accordingly.
Should be something like this:
<!-- Google tag (gtag.js) -->
<script async src="https://www.googletagmanager.com/gtag/js?id={{ $gaid }}"></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}
gtag('js', new Date());
gtag('config', '{{ $gaid }}');
</script>
I would have reported this as a bug but the issue tracker is disabled…