There may be different reasons for that. Maybe the extension doesn't work on your side for some reason. Or you use private browsing but you didn't let this extension to work in it. Or you have some other extension interfering. Or you really visit websites the extension doesn't cover yet. There are tens of thousands of different cookie warnings, and many websites change theirs too frequently and make it more difficult to remove the pop-up easily. Feel free to report those websites properly (via the "report" link in extension's menu) or by writing directly to author@i-dont-care-about-cookies.eu. Thanks :)