Just to make sure it's clear, if you click the little dropdown in the lobby setup screen you can select how many teams the players will have, once put into those teams, they are locked. If you're on an 8 player map you select 8 teams and each player will be placed into a separate team.
Hmm ok then that is what I had it set at. I could swear though when I jumped into a multi-team fight that the AI ships ignored each other and focused me (outnumbering me). I stayed to fight but ultimately had to retreat. I'll double check next time it happens just to be sure though, could be my mistake.
I DID however encounter a problem with my Titan getting stuck on my starbase when it was "above" the starbase. I had to self destruct the starbase to save the titan so it could move, but that's another matter and relatively minor I would think.