The topic listing is done wrong.
It's done after the last time the node has been edited, instead of the last reply.

The issue does not reproduce if I disable the module, thus letting the core forum module list my topics.

Look at the times in the "Last post" colum in the screenshot below.

Files: 
CommentFileSizeAuthor
issue.png237.29 KBrizedr

Comments

Looking through I'm tempted to believe that the issue comes from views.
core-overrides.inc

Category:bug» support
Priority:Major» Normal
Status:Active» Closed (won't fix)

It's not a bug. It's a feature :)

Sorting is done by 'last updated' date instead 'last reply' by design. If you don't like it you can change sorting behavior in Views settings.

I'm not going to change the status because I don't have time to confirm... I have this fuzzy memory of having changed the default on this in D6, though. It might have only been on my site? I'm not sure. At any rate, this _might_ be a regression from D6. If someone has an unmoddified D6 AF installed and wants to check, that would be great. The only D6 I have is heavily modded so no good as an example.

Michelle

Any suggestions for how to change this sort in views, then?

I just imported 150 old forum topics, all of which are now at the top because of "updated"