User blog comment:Rappy 4187/Technical Update: April 30, 2013/@comment-5887706-20130430163748/@comment-452-20130430191925

I reported this problem about 24 hours ago, no reply yet.

It appears to be a problem with the notification cache. As we all know, there's 2 types of notifications, Message Wall/Forum reply notifications, which are shown in your notifications where-ever you are, and forum highlights, which are only displayed when you're looking at that wiki.

It was explained to me recently that when you visit a wiki, all new forum highlights are copied to your notification cache, but it would appear that there's a bug which is marking new forum highlights as global notifications instead of local notifications.

So when you visit a wiki and get a new forum highlight notification, you'll continue to see it when you visit a different wiki, if you haven't marked it as read.