I just started my first game on the Auriga map. I am playing a "true start" game by slotting the factions in using a multiplayer game even though its just me playing against the AI. I am playing as the Vaulters and just started exploring the world around turn 160 on normal difficulty, normal speed. Every AI faction only has their starting region. They haven't expanded their borders at all. Is this expected behavior or what might be causing this?

I've played a lot of EL and never seen this issue with the AI but I don't play the Auriga map at all so I'm blaming it.

I would try exactly the same setup but don't use that map as it was known to cause a lot of weird issues and had to be patched a few times already I believe.