This is likely caused by a room which is unplaced, or a room which is unbound. Check the area of the rooms in Dynamo and filter rooms with an area !> 0. Also it’s best practice to make sure you are reviewing a room schedule with no filters periodically to ensure these are taken care of in the project.
I would add here that I often include an additional check to see if a room.Location point !null because I have seen rooms get sandwiched under finish floors and slabs that are bounding but don’t have area. Not super critical, but has saved me before.