As you can see on the mini-map this is a large room, but as you can see on the screen it’s just a small empty corridor. Any ideas? I can’t see any dwarfism entrances.
Whenever a room occupies a larger space than that which you can see, there is usually something hidden nearby. You may be able to pass through at a certain point in the floor, go through a wall or the roof may have holes in it. Places you can pass through are sometimes painted with a slightly darker color than the surrounding edges. To check the floor, attempt to jump down through it like you would a thin platform by pressing down and jump. Often treasure and fairy chests can be found at the end of a labyrinth of hidden passages.
Sometimes you encounter a room where monsters will be present in unreachable areas but able to attack you. These can sometimes be the objective of a fairy chest and you need to kill them using spells.
Finally that room may be a room whose purpose is to connect other rooms together by passages but in this case no other rooms were placed on the other sides of that room, resulting in a terminated connector room. This could be the case if you can’t jump into the walls anywhere and there are no chests or enemies present.