We had some similar situations.

• A user (wrongly) attributed a school music room (studio) to a teacher (Marko). The scheduling program left the studio empty, every time Marko had classes in a school 10 kilometers away. Which was quite difficult to notice.

• elsewhere, the same program was instructed to minimize student travelings between two buildings 1 kilometer apart. Each buildings had several rooms and the distances between each of them were given by the user, who forgot to count the cafeteria in one of the buildings into the list. So the program concluded that the distance from the cafeteria to anywhere is 0 and managed to build a schedule with no student transfers at all. They have been always "teleported" through the cafeteria into another building. This one was spotted soon enough.