When the top (or handrail) profile is offset from profile family centerpoint, it will display wrong in the plan view.
The railing is displayed twice: (A) once in the correct position that is also shown in the section and in 3D, and a second time (B) as a dummy element that has the same width, without any interior projection lines and in the wrong place.
My impression is that Revit assumes that Top Rail profiles have to be centered on the centerline of the profile family. If the profile is not centered, the the dummy rail will show up. The B seems to be constructed so that Revit finds the actual centerline and width of the profile, and then draws the B rail offset by the correct value from the placement line of the railing and in the actual width.
Here's the profile, I've intentionally offset it from the centerline, to make the bug clearer to see. It was intially touching the centerline (like a continous railing on the wall), then A and B were overlapping slightly.

This is the plan

And the section, notice the reference plane and that only A shows up.

Is there some way to correct this behaviour? I think this should be reported as a bug.
I've attached the revit file for clarity as well.