I got stuck in this as well. The problem appears to be that you can glitch through the barrier (second picture attachment) without collecting the Tome to drop the grate. It's possible to Travel to the second stage of this map by this method without having collected the Tome from the first stage. Without the Tome the final door will not open.
In my game it was on PS4 in a two player internet multi-player game.
Either move the travel portal further from the grate so that the travel hit box does not reach outside the grate, or reduce the hit box size.
I got stuck in this as well. The problem appears to be that you can glitch through the barrier (second picture attachment) without collecting the Tome to drop the grate. It's possible to Travel to the second stage of this map by this method without having collected the Tome from the first stage. Without the Tome the final door will not open.
In my game it was on PS4 in a two player internet multi-player game.
Either move the travel portal further from the grate so that the travel hit box does not reach outside the grate, or reduce the hit box size.
See also
MCD-1356on XBox and PS4