ductwork not showing on plots or pdf files

[pagioni]

see attached links: I seem to have random duct fittings/branches not showing up on plots. This happens when I plot directly to the plotter or from a pdf file. All branches are connected to the main and the grilles are connected to the branches. MEP hidden line setting : gap is set at 1/16. I feel like I am missing something in a setting, since my model looks accurate. Any help appreciated.

[CoreyDaun]

I've heard that this problem stems from plotting Raster versus Vector. Try plotting those same sheets/views as Vector, which might be a little slower.