There are three threads in the Skyscrapers forum. None of those three threads are flagged as being unread or as having new messages. All have the "unbolded" text indicating that I have fully read those threads.
However, when I look through the forum listings, the "Skyscrapers" forum indicates that there are one or more threads in the forum I have not yet fully read. Clicking the "Mark Forum Read" button doesn't help.
EDIT: Same thing also with the Past Masters forum. All threads in the forum are fully read, but the forum still shows up as unread in the forum list.
However, when I look through the forum listings, the "Skyscrapers" forum indicates that there are one or more threads in the forum I have not yet fully read. Clicking the "Mark Forum Read" button doesn't help.
EDIT: Same thing also with the Past Masters forum. All threads in the forum are fully read, but the forum still shows up as unread in the forum list.