Your best bet might to be let someone look at the map itself to have any idea why that may have come about.  At least if it has anything to do with the map design.

In the meantime, I suppose you could check to see if the map has any one way phase lanes (I believe technically possible via wormholes, I forget if actually possible otherwise), double check the spawn chances of planets and lanes... and that's all I can think of off the top of my head that might prevent the ai from moving about more.  At least doesn't fall out of the map side of things and into the modding side.

Thanks guys. I only came into contact with 1 Ai, so I'm thinking he was set on eco or something, and just didn't want to attack me.