Every save file crashes at 4am

Every single save in my game crashes at around 4am in game time. I have tried EVERYTHING to fix this. Removed all mods and CC, restored save files, deleted cache files, repaired game via steam, run as administrator etc. The game goes completely unresponsive and needs to be closed via task manager. Ctrl + F4 does not work. I started 5 different legacy challenges, only for this same problem to appear in every save, after 2 or 3 generations. Always around 4am game time. Please has anyone found a fix? I have played for over 1500 hours and NOW got this problem. I have spent unholy amounts of money on this game.

Thank you!