[In dual extrusion, second material sliced every other layer]

The thing is that the problem occurs "within" the horizontal cylinders. When I enlarge the cylinders using the CAD software and I slice it I see more alternating layers, i.e. one layer with both materials and one with only "material 1".

1) Attached are some screenshots

2) The CAD is Autodesk's Fusion 360 

 

[In dual extrusion, second material sliced every other layer]

I am attempting a dual extrusion job. In the design, I have some solid cylinders (material 2) oriented horizontally and spanning several layers within a larger cylinder (material 1) which is vertical.

When I slice this, the horizontal cylinders are sliced only every other layer so the printer extrudes "material 2" every other layer while "material 1" is extruded every layer.

Any idea of the reason this is happening and how to resolve this issue?

 

Thank you!