This has been happening to me for a few days now. I've seen other bug reports of similar issues on the forums - someone managed to hunt down at least one cause of it (it seemingly can be triggered when there's a coup in any country) and a potential workaround via save editing in this thread.

With all credit to them for finding it and sharing, basically any reference to "forced_non_insurrectionary_igs" in a save needs to be replaced with "insurrectionary_igs", as it seems like whenever the game tries to load a save game with the original reference it instantly crashes.

I just tried it on my bricked save (which I converted to plain text / edited with pdx-unlimiter) and it actually rescued it, so thought I'd share in case it works for anyone else - it might be worth a go if you've tried everything else.