I can confirm having the same issue (Firefox 30).
What I found so far:
Turned on tracking ( in config/global.ini.php:
- [Tracker] section set debug=1
- [log] section set log_writers = file, log_level = VERBOSE, logger_file_path = /tmp/piwik.log
This resulted in the following lines in the log:
DEBUG PrivacyManager[2014-06-27 20:25:49] DoNotTrack found.
DEBUG Piwik\Common[2014-06-27 20:25:49] Visitor excluded.
Installed Live HTTP headers in Firefox and checked the request and what do you know:
This DNT is the mark that is supposed to tell if you want to be tracked or not.
DNT (Do Not Track) set to 1 means: do not track me. And Piwik abides by this rule (as one of the few I imagine).
However the silly thing is that my Firefox 30 currently is set to ‘Tell sites that I want to be tracked’ …
It would appear to me that the problem is with Firefox not setting the DNT flag right.
But it does explain why Piwik is ignoring it, at least for me.
Hope this helps.