Hi @StanStill ,
What darktable version do you use?
With 2.6.0 (but in Ubuntu Linux) there are no problems with saturation neither with the representation in the darktable nor with the export as JPG:
Exported JPG:
I get a desaturated image like in your example if I choose the linear Rec709 RGB profile instead of standard color matrix in the module input color profile:
This is how it looks in the darktable:
Something seems to be mixed up with your color profiles.