It's definitely 3.2.1. However, I think I know what's happened. I inherited this site, which has been running for many years and has accumulated a lot of garbage along the way. Consequently, some of the files (e.g. images) exist outside the phpbb directory that belong in there. Correcting that has fixed most issues other than BBcodes, but I'll sort that out soon, I hope. I no longer have access to the original server, which would have helped.