Zero-length movements prevent visualization.

[danfitz7]

Zero-length movement commands (either zero-length relative moves or absolute moves to the previous position) will prevent proper visualization in MayaVi because it can't calculate their normals.

This is especially a problem for extruder-only commands because they never have any xyz movement. For example, calling g.extrude(5) or g.move(e=5).

[jminardi]

I will look into this. This almost seems like a bug in mayavi