Right, just migrated on my forum index page I've got each forum and one topic title (newest) is shown below. However on one forum it shows a topic that's 17 years old and despite new topics being created it doesn't change. Do I need to reindex something or something else going on?

I had a play and look around but couldn't find anything it does have subforums underneath, but another one lower down is the same and doesn't have this issue. Thanks!

There is an open bug report for that issue at present