These are all circles, but only some areas are extrudable, why?
I’m working on a geared design, but using imported dxf gear patterns are waaaaay to slow to work with due to all the control points, so I’m forced to use simple circle representations.
Idea: When locking a sketch, don’t search or display control points during selection. I think this would speed up the workflow to… usable. 
Suggestion: you can download a variety of gears in STEP format from McMaster. They can be imported and used in Shapr3D. I use them all the time.
I assume your overlapped double circles represent the tooth height, yes? When I design a gear train I only need to use the pitch diameters to determine center to center distances. Once done I can establish the shaft pins and then use the Align tool to center the appropriate gear.
And yes, that’s an odd sketch anomaly where you had to restart the app.
