[Solved] bars of puzzle pieces recessed ??

[hdlbq]

Hello,
I have a strange problem with Simplify3D 4.1.2 on Mac.
My design is a kind of puzzle, in which the pieces are tied together with "bars".
These bars are merged with the bottom of the puzzle
A photo of this is attached.

Thus, the bottom of my piece is either empty or flat, never recessed.
But the preview of the gcode shows strange recessed bars.

I joined the factory file.
Thanks for any help.

Solved: the problem was in the model. Even if Simplify3D doesn't show anything in it....
I'm not ready to pay $60 more for upgrading such a software