That's odd. I actually unselected some lists and white-listed some sites and the problem persisted. I disabled the extension and all sites started working as us

That's odd. I actually unselected some lists and white-listed some sites and the problem persisted. I disabled the extension and all sites started working as usual again. I am running Chrome 39 on Windows. I'll give it another try now - will uninstall / reinstall to make sure the default lists are being used.