Trouble with Artisan extruder

Hi - I’m a Sketchup modeling novice having fun trying to learn the Artisan extension from YouTube tutorials. The trouble I’m having is that I can no longer extrude my subdivided / smoothed (iteration 4) geometry, despite having achieved it once the other day. I’ve created a sphere, made it a group, selected it and tried to edit by way of extrusion - to no avail. The tutorial I’m trying to learn from gets to a point where a sphere like mine is existing inside a light blue box, but I can’t seem to make this happen. Here is a screen shot from my try…

Go to Artisan settings and turn on ‘create proxy from group’