Something that may have been missed, earlier. There are two separate, and probably totally unrelated problems here. ScubaSteve and UsryTegre have an intermittent problem where sometimes the last page of a long thread doesn't work properly. For example, they are on page 156 of 157, they click 157, but page 156 displays instead. This does not appear to be affected by the number of posts on a page. This is NOT the problem that I and the OP krawlings have.
Our problem happens on all threads that are over one page in length, and appears (in my case, at least) to not be affected by display mode, I have tried with all of them. This problem is tyhat any page past the first one will display, but as soon as rendering is complete, it immediately reloads page one. This only seems to happen if the number of posts per page is set to some number higher than default, in my case 50.
It seems there is a workaround for it (set postcount to 30) but it is rather annoying. With my reading style, I would prefer an option of (display all posts) as I HATE having a thread broken up into pages. I want to see all of them. An alternative that I would rather like would be a way to instead of being able to jump to the first unread post, or last post in a thread, jump to the page containing the first unread post. That would be a LOT more useful, and isn't what it currently does...
So to make a long story short, the reason you are getting inconsistent feedback on this problem is that there are two unrelated problems that are being reported in the same thread. One is very reproducible, and one is very intermittent...