cad mep 2013. in paperspace i have several viewports. the one in plan plots correctly, b&w, lineweights.
anything not in plan plots in color with no lineweight. also ive got them plotting with the "hidden" visual style. (it doesnt matter what syle, all plot in color) the end result is on color and many lines are missing from pieces of duct, equipment, ect. in each viewport
Couple of things to check:
1. Make sure the variable HIDEPRECISION is set to <1>. This will help with some of the lines that don't show up.
2. Set the properties on the isometric viewport to "Legacy Hidden". This can be found on the properties palette under shade plot.
Another tip you can do is override the layer colors in the viewport to a color that prints monochrome (white) so they all print to the same line weight.
I attached an example from our office that I did with those same settings and should give you the results you’re looking for.