A multilngual WordPress Websites with 2 additional languages which are used on dedicated domains uses the following JS tracking code:
<!-- Matomo -->
<script type="text/javascript">
var _paq = _paq || [];
/* tracker methods like "setCustomDimension" should be called before "trackPageView" */
_paq.push(['trackPageView']);
_paq.push(['enableLinkTracking']);
(function()
{ var u="//<matomo.domain>/"; _paq.push(['setTrackerUrl', u+'piwik.php']); _paq.push(['setSiteId', '3']); var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0]; g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s); }
)();
</script>
<!-- End Matomo Code -->
The Matomo log records show requests for the other domains within the main domain, but should record and count them for both other domains in Matomo (Matomo URL request paramter Site=nn). This has worked earlier and now it is not clear why the requests are not recorded for each domain.