I enter here after month of absence (and I not received no one mail notification from this time - maybe luck, provider or bug) and use "Show unread posts since last visit." It gave me three pages of posts... but it seems, it gives it wrong. At least, I seen identical entries on first and second pages, and I see three topics already, that I didn't see in this list, but marked as "new" for me in particular branch.
If it is not my imagination (bug in my mind ), then it means that this "new posts" function works wrong: it sorts out posts' list differently each time, when worked. In that case it cause problems, when this list more than one page long (because some posts can appear on "invisible" pages for every one selected page, "evading" me).
I seen exactly same problem on Steam, when it is not enough key parameters (for example, sorting by price have this error). If it is reason of such behavior of HotU - please, fix it, adding time as additional key parameter (for example). And if it is my own fault - I am sorry.