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 Hidden Line Visual Style.
To see all visible lines, Revit recommends that you first create an opening in one surface before passing another surface through it. See Editing the Profile of a Wall.
Intersecting geometry in hidden line mode (no edges are created at the intersecting surfaces)