Yesterday I visited the news forum and all the threads were marked as read even though I hadn't opened most of them.
Today I went to the news forums and it appeared that the red stars we're working properly for the thread subjects list. But once I entered a thread none of the posts would have red stars denoting where I previously left off. I then click the New Forum again and once again all the red stars I had just seen were cleared thus making it look like I had opened every thread.
Using Chrome, haven't messed with my cookies or any internet settings really.