I'm getting an "insufficient slab or faulty slab axis" error in the geometry check. The tile in question does not appear in the drawing. When I try to find it with the object finding command, it says found, but when I select it, it does not select it. I get the same error even if I delete all the tiles on the floor with ctrl-a. I get a similar error when I try to analyze. I would appreciate if you can help me how to get rid of this error.