When i alt tab while a savegame is loading, it stops. this happened to me a few times. normally I would just alt+f4.
But the last time i tried pressing escape to get back to the main menu, however when i pressed ''save and quit'' it saved the broken game. So i couldnt play my game. luckily it was only an easy game on 50 days, but i can imagine i'd be pretty pissed if it was a harder game.
Have a nice day!
''Loading failed. there is no command center after loading the game''