When I draw a vertical Line on top of another Line I don’t get any end point which I can snap to. An Edit point isn’t even visible when I activate PointsOn (see red ring). But drawing the line horizontally doesn’t have this problem (see green ring):
Rhino 6.32.20337.13001, 12/02/2020
How cool is that?
Edit: And, it has the same problem even if I draw it horizontally and then rotate it vertically. No endpoint visible nor can it be snapped to.