It’s difficult to reproduce quickly, simply because of how randomly it occurs. I’m playing with animations on, and when the lock occurs, all animations stop.
I think I’ve narrowed it down. I was simply walking towards a car to try and start it to try to get the game to lock up, when the game locked up. I had done nothing more than take a step. It’s hard to tell, but I think it occurred when the weather changed naturally.
I’ll try that next time and see what happens.
Edit: It’s not related to the weather changing. Might have another error that could be related. A map gen error that occassionally appears. Something about being “The following special could not be placed: Cemetery_Religious” Sometimes it just says “The following special could not be placed:” without any special location being displayed at the end of the line. That error also appears regardless of whether mods are in use or not.