Problem with extrude acting strange

[ddufford]

I am new and trying to work through this online tutorial: https://www.youtube.com/watch?v=A5bc9c3S12g&t=18s 

Seems that when I reach a point while extruding the first round circle, when something goes wrong and the extruded face turns to a hatch pattern and won't extrude further in the positive direction.  It will extrude far into the negative direction.  Once the hatch pattern appears, if you complete the extrude, you can no longer select the face.  Seems like a bug.  The extrude will go to 8.5mm but fails when it gets to 8.6.

Tried opening my project on a totally different computer and it acted same way.  See attached .pdf for screen shots.

[TheCADWhisperer]

Do you have an active Section Analysis?

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

[ddufford]

Attaching requested export.  Thanks.

[ddufford]

Attaching requested export.  Thanks.

[ddufford]

Absolutely correct.  Thanks much for very prompt reply.  Really like your "video solution".

Dennis