I am having the same problem as sebiche44.
Spent a whole workday trying to get dual extrusion to work on Simplify3D 4.1.2 on my work PC, but the slicing result was always an empty view with 0 time and 0 material consumption listed. I tried multiple dual-extruder FFF profiles people had posted online, tried using the traffic cone files from Simplify3D's tutorial, never got a dual extrusion to slice. I could get single extrusion to slice, or using different profiles of a single extruder at different heights, fancy things like that, but as soon as going to dual extrusion was selected, the slice output would only be that blank platform with 0 time and 0 material.
Frustrated, I tried this again on my home PC with my own copy of Simplify3D 4.1.2, and on my first try I was able to get successful dual-extrusion slicing. I tried a variety of things, but it basically always worked. So I saved out the Factory File and FFF of the traffic cone example which I had set up as dual extrusion and would successfully slice, and went back to my work PC, imported those, and the result would fail to slice.
This matches what I see in this thread, where horst.w can get a successful slice of sebiche44's Factory File even though it comes up blank for sebiche44.
Work PC (dual extrusion fails to render) Windows 7, Intel CPU, Quadro graphics, Simplify3D 4.1.2
Home PC (dual extrusion works) Windows 10, AMD CPU, GeForce graphics, Simplify3D 4.1.2
I submitted a Contact Us request on Simplify3D for tech support for this software issue, I will let you know if I hear anything. I'm also trying to get this software obtained on another similar-spec work PC, so then I'll have another one to test, trying to find out if it's PC incompatibility or just a glitch in how it got installed on my work PC, or just what. I already performed a "Reset All Settings" on Simplify3D on my work PC, yet the dual extrusion slicing problem remains.