After GetPoint.Get calling, mouse cursor change to deny

After opening the attachment, DO NOT rotate, move, scale camera

Just draw polyline via _Polyline command

It’s harder to find this angle, I’m new to draw a simple Solid and can’t reproduce the problem anyway

未命名.3dm (3.0 MB)

Hi -
That is expected behavior.
Your CPlane is only accessible in the lower part of that viewport:

When you try to draw something above the horizon of that CPlane, you will get the “no parking” sign as it is not possible to project the point to the CPlane in that part of the viewport.