We have just spent the last 1.5 hours reading forum articles on possible solutions (and causes) to this issue, with no success. After logging in as Admin our dashboard shows zero visitors since Jan 10th. When we login to Google Analitics we can see lots of visitors over the last two weeks, so something is causing Piwik to not track.
Nothing has changed on the website in the last 3 weeks with the exception of a few text updates on some articles, and running two Piwik updates. We have read several forum posts for similar issues and have tried everything we could find- clearing browser cache, trying different browsers, copy and paste piwik tracking code from Dashboard-Settings, deleting all files in /tmp, and re-uploading a fresh download of the current Piwik files.
We have an inhouse data center and control/manage our own webservers. they all run CentOS 6.4 with the latest stable versions of cPanel/WHM, php, MySQL etc. We have seen no other issues with broken scripts or modules on any other websites, so the cause of this issue is a complete mystery to us.
We LOVE Piwik!!! THANK YOU sooo much for creating such a superior product to Google Analytics.