i’m using self hosted version of latest piwik 2.15.0 together with plugin customoptout 0.4.0.
i have different websites with different ids.
for all sites tracking with piwik is allowed.
if you are visiting one website and change piwik setting to do-not-track and leave site then visiting another of your own websites and check piwik settings here … it is also set to do-not-track - independent of other idsite parameter.
same procedure from the other side.
The author of the third party plugin is answering the following:
The optout handling is managed in piwik core. So i think this issue is related to piwik and not to this plugin.