Summary:
Certain monuments in some worlds have rooms which are not accessible.

Steps to reproduce:

1. Create a world using the seed -5876593976426158814 and teleport to 744 40 -185.
2. Give yourself night vision.
3. Enter the monument through the entrance and try to locate the boss room by traveling every corridor.
4. Teleport to 733 40 -212 and try to locate an exit or a corridor that leads outside the monument.

Observed results:
There isn't any way to enter/exit the boss room, as all entrance corridors are blocked off by walls.

Expected results:
The boss room should be accessible from the outside.

Original description:
I was raiding a monument in my world and noticed that there didn't seem to be a way to the core room after checking every way from the entrance

Seed: -5876593976426158814
Coords: 744 40 -185

Screenshot is of all the accessible areas cleared and drained

World linked is the same area of the same world shown in the screenshot, same seed as given above