Current behaviour
When Revit decides whether to display an element in a view, it tests all family geometry against the View Range — including geometry that is not modelled: symbolic lines, masking and filled regions, text.
As a result, 2D graphics extending beyond the outline of the element's solid geometry cause the element to appear in views that its actual geometry does not reach at all.
With symbolic lines this is confirmed: removing them from the family stops the element from appearing in a level where it does not belong. Autodesk has also confirmed the underlying mechanism on these forums — adding a line to a family changes its bounding box.
Typical case
A family contains a symbolic marker drawn in two planes so that it is legible both in plan and in section. When the element is rotated 90° around a horizontal axis, the vertical plane of the marker stands upright, crosses the floor above and the element starts to appear in the plan view of the upper level — even though its solid geometry is entirely within the level below. The drawing then shows an element that is not physically there.
This is not limited to one category. Any family with symbolic graphics extending beyond the outline of its solid geometry behaves the same way.
Request
Whether an element falls within a view should be determined solely by its modelled geometry. Anything that is not modelled and serves only for annotation should not enter this calculation.
This does not have to apply everywhere
The current behaviour is deliberately used as a workaround — an invisible line is added to a family so that it reaches the cut plane and the element becomes visible in plan. That workaround must keep working.
Revit already treats categories differently in this respect: only Windows, Casework and Generic Models are shown above the cut plane. Extending that principle would be enough — let the behaviour be defined per category, or as an option on the geometry itself, so that each family type can be set to whatever makes sense for it. Nothing existing would break.
