If the model includes intersected geometry (for example, an extrusion passing through a wall surface), Revit does not create new edges along the lines of the intersection. This may result in incorrect hidden line removal during export. If you attempt to export a view of the design with hidden lines turned on, you may see unexpected results when you open the view in another CAD application. See .
Intersecting geometry in hidden line mode (no edges are created at the intersecting surfaces)