I have noticed the same problem. 

I'm not entirely sure but I think when you create a game, if you change any of the default AI personalities and then later save and reload the game, the changes you made are lost. It's like this selection is not stored in your save file, and you are given the default players. When I do this, I just try to remember who was who and re-assign, but it feels tedious and un-necessary. 

I play a multiplayer game that, like others, is suffering from a lot of disconnects. This, paired with the AI personalities resetting is super annoying, as every time it disconnects, I need to re-configure the AI personalities. 

same happens to me. It doesnt seem to affect gameplay other than looks, however. All their original traits and even name seems to remain.