I have a similar problem with that feature. When I click that little gray arrow sometimes--maybe about 50% of the time, and I think it is only with quite large threads--it does not direct me to the last page. A different problem is on my homepage. The Post and Preview buttons no longer have those words written on them, though they still work fine. I am running Mac OSX v4.11 and use Firefox for my browser, in case that info is useful.
Neither of the above problems are preventing me from enjoying the site. You are doing a fantastic job!