So I've run into a weird issue with my copy on the Xbox.
I was playing the second Patient Zero mission and the "Saving" icon seemed to get stuck on screen, the game was perpetually trying to save and opening the pause menu the save screen was greyed out, even after leaving the game for about 10-15 minutes. I closed and quit the game as it was impossible to do anything else really, but now when I try to launch it the game just hangs on the title screen.
It works until I press A to start playing, and then it just sits there. The "A PLAY AS <profile name>" stops flashing, the music keeps playing, but nothing at all happens. If I press Y before anything else then the profile switch screen comes up, but again, as soon as Press A to try and launch the game even under a different profile it just hangs perpetually. At this point the only thing I can do is press the Xbox button on my controller to leave the game and quit it.
I've tried this with the Xbox in Offline mode as well, as I've noticed seriously slow performance with some of the menus when in online mode, but it makes no difference whatsoever.
Edit - Did a Full Shutdown on my Xbox and that looks to have resolved it, though all my autosaves from my last session have gone.