I'm seeing 2 similar issues. The 'page:' links for the last 3 pages aren't working, and somewhere between 1/4 and half the threads are gone (entire days are missing/inaccessible); it's not a per-page display thing as going to the next page "jumps" quite a bit. This is verified by clicking, say, the last thread on page 1; the "previous thread" link goes to a thread that's not listed on either page 1 or page 2.
edit: never mind. the problem with pagination - which should default to 30 topics - was with logged in users who don't have a preference set. You can set the preference to fix it right now, or just wait a bit.