I have done some testing on Studio concerning Zombie mode.
Here is what I have observed:
When a player leaves the game by actively clicking the leave button everything works as expected: the Zombie pass function is called, which skips the Zombie, if written correctly, of course.
When a player is expelled after having run out of time, it does not work. The expelled player's turn is not skipped, the game gets stuck. This happens in Studio and with published games.
There is a strange effect, at least on Studio: The expelled player does not get expelled. He can still make a move. There is a "Get back to the game" button which has no effect when clicking.
The Zombie mode state is not entered, the function is not called. The log lists functions with other names. So is seems that there is nothing wrong in the zombie pass function, but some bug in the framework?