Checked between here and the same thread on a different instance and noticed sorting comments by old doesn't seem to be working here; that is, selecting the option on the web interface displays no comments whatsoever instead of sorting their display. An odder issue that I'm not as clear on is older comment fetching/display. In one case I found them not showing up here, but also not on the thread's home instance either, so I'm not sure what's happening there.
In another I found them not showing up here, but they were showing on their home instance (different from the first, which may be why the difference).
Btw, checked on this again and it still appears to be the case. Also interestingly, it applies to sorting posts as well, whether set to Local or All.