Sorry for the long rely time. Life got in the way...
I think I found a repeatable bug.
90% of the time I work in mm, but I just got a couple requests to design a few things using inches.
To my surprise, when I exported stl, it object was very small.
After your helpful reply, and a little experimenting, I realized that your stl export converts my 10 inch cube, to a 10mm stl!
Please add this to your next release!