Plasma's system tray only shows applications that have marked themselves interesting - the rest you have to click the popup to see. Akregator always marks itself as interesting even though there are 0 unread items - this is waste of the system tray and not so elegant. Reproducible: Always
it doesn't use new system tray. Will not port until akregator2 will release.
Akregator is now only visible in the tray when there are new articles. (version 4.12.60) Thanks.