Unable to edit - so a new reply is in order.
For example, this morning I noticed a new thread in my forum entitled "Happy New Year" which had 15 replies. I had never visited that thread.
In threaded mode, I opened up the forum and noted that the thread was correctly highlighted in a different color (which I manipulated by the way in the stylesheet editor - which I cannot do any longer at the reply level in the new version) and there was the appropriate "new" folder icon.
However, when I clicked into the thread, all 15 replies were marked as read. Not one had the "new" folder icon. But when I clicked into each reply, there was the "new" folder icon. It just does not show up in the threaded reply listing.
On the other hand, there was another older thread that I had not read, which was not marked at new and when I clicked into it, all the replies listed in the threaded reply list had the "new" folder icon.
I get the same kind of results here in this forum.
Finally, some of the time, in threaded mode, in a new thread with a new folder icon, when clicking into that thread, all the replies are correctly identified as new, with the new folder icon, but if you click on the last reply, first - all the new icons disappear and all replies marked as read.
I don't know what is more frustrating - trying to articulate the problem or experiencing it