When placing any type of linestyles the scale is so small that you need to zoom into them to see them. Otherwise, the lines look solid from a distance and also plot that way.
The working units used in the main 3D model were different from the files that are referenced into it. The main model was in metric units, 10000 per mm, and the reference files were in imperial, 304800 per foot. All files must have matching working units.