Open Akregator to see all messages, old, unread and new. Then use the search bar and check the left icon to choose the filter 'new'. Now you see only new messages but they become to mark read immediately. This is without further actions from the user! So after this you see no messages. If you change the filter to 'all', you see all messages as read.
*** This bug has been marked as a duplicate of bug 350731 ***