Even in flat mode the "past xx hours" active topics doesn't work as expected, it still only displays the most recent post.
I see why all the threads are getting out of order now since everyone is using the flat mode, people are replying to one part of a thread under another part.

I just switched my stuff settings to flat mode, and in just a few minutes of browsing I can see a huge difference. Thanks all of you, I think that solves my only gripe about this sight!