I think I know why people can't save. I had the same problem, and I think it has to do with on which console you bought the game.
I have 3 xboxes and thr game only lets me save on the xbox I bought the game on. Which shitty enough is my old console at my parents house, where I was with christmas when I bought the game. At my home console I can't save the game. Only on the xbox I bought the game on will it let me save
So bad luck if you have more then one console, like me. I guess this is the problem everyone has that can't save.
This is total bullshit. They obviously didn't account for the people that have more then one console. This is the first game I come across that does this like this
Thank you Frozenbyte for this stupid ass shit!