Sometimes the level does not end when the crystal enters the exit room. You need to move the carrier out of the room and back in to make it work.

I had a similar issue today in which I could not exit the second floor. My four heroes were all in the exit room with the crystal and nothing happened. They kept fighting and eventually got killed when I was out of food.



I didn't try to make the carrier go out and back in the exit room, but I'll try it if I have that problem again.