Crashing during Campaign mission 3

Hey Devs,

I'm getting some major crashing turn 400 into the third campaign mission. Unique situation since it shouldn't take so long (i like to turtle hard). Anyway, at a certain turn I stop being able to save without crashing the game. A few turns later the map starts to appear like i have influence everywhere, then reverts to normal. A few turns later I crash. It's a very reproducible issue and happens at the same exact turn. Any ideas?

Thanks! it's looking good otherwise.