My Piwik which is self-hosted on my website using the latest version of Wordpress 4.2.2. Piwik stopped recording suddenly on 11th May 2015. I can still access the Dashboard and Visitor Log but the recording of visitor activities has stopped.
I updated my Piwik to the latest version 2.13.1 on 9th May 2015.
I checked my Wordpress footer. The Javascript Tracking Code does not work any more. Try reinstalling it.
This is what you should do :
Go to Administration/Website/Javascript Tracking Code and view the tracking codes.
Go to your website and install the Javascript Tracking code into the footer of your website.
Disable the “Exclude your visits using a cooke” so that your visit to your own website is being tracked.
Clear your website cache.
Surf onto your website and alternate between to 2 obvious pages on your website and then check Piwik again. It should starts to record your visit again.
There has been several security updates from Wordpress lately and from the various Wordpress plugins. I think it is screwing up the Piwik Javascript Tracking Code.
You may need to review if your Javascript Tracking Code is still working and switch to using the Image Tracking Link if need be.