I am on the Xbox one version of this game, and today I discovered a bug that stops my saves from staying saves after I close the game. I stared my campaign online, but today I was not able to play online, so I loaded it up offline. After playing for 3 to 4 hours, I saved, quit, and closed the game. I came back later today to find that my saves had reverted to where they were before I played for 3 to 4 hours. I then decided to try again and loaded my save then played from there for a few more hours. I then saved, quit, and closed my game again. I came back to find that my saves had reverted back again for a second time. I don't know what caused it. But the saves stayed while I was in the game, and I was able to load them in the same session, they only disappeared after closing and reopening the game.
