Fusion 360 M3D Slicer
FMK, I loaded the two STL files, top.stl and bottom.stl into Meshmixer. Using Analysis, Inspector, no errors were found in the models. I then loaded the STL files into my slicer, Simplify3D. Due to common Y/Z exchange, the models were loaded in a vertical orientation. It was simple enough to use "Place surface on bed" to get things "squared up."

The g-code preview showed also no failure points.

My first suggestion would be to ensure that you have your model flat to the bed. I've run into too many Thingiverse models that the creator made with a non-zero planar reference, that is, the model was tilted a few degrees.

You say that you created the model in Fusion 360, which would imply that your model is square to the plane.

I'm not familiar with M3D software, but if you have the option to use a different slicer, use Slic3r or Cura to see if you have the same results.

As it stands, I'd consider no fault in the model files.