After destroying the Lich it never actually blows up and shortly after that the Mammoth drives into unloaded level and everyone dies. I have even restarted the level from the beginning and am unable to progress.
Same thing still happens to me after update 2. You go on a “magic carpet ride” where the Mammoth can somehow drive off a cliff where warthogs or feet cannot go. Get inside the mammoth and eventually it disappears and Chief is left trapped hundreds of feet in the air and unable to walk. Trapped no matter what part of Mammoth you are on when it disappears.
Good to not be the only one with this happening