When you use the Room Overlay and mouse over one of the rooms. It's missing the critters information.
In the first image, there are some shine bugs in that great mess hall. In the second image, i'm mousing over a regular room and it shows the number of critters in that room.
Some of the rooms seem to be missing critter details.
Make a room such as great hall, and put a critter in it. roll mouse over room and see that critter info does not appear in room detail.
Remove a building such as a mess table and it will revert back to a 'room' and you get critter info in the details.