I have the same exact problem. Everything else works fine, but splitscreening freezes the system. In extinction Mayday it always happens at the same spot, when the drill finishes on the operating rooms door. In multiplayer it freezes when the game ends on the new maps. Only on splitscreen.
I chatted couple of hours with the support people last night and tried everything they suggested, to no avail. This is really frustrating, because I always play splitscreen with my friends.
Please fix fast!