Your DWG file's lines all have override LWEIGHT settings: LWEIGHT settings have nothing to do with plot style tables or output. Any reason you've never turned that off?

The PDFs posted by a fellow user @maxim_k above do indeed have line weight settings. Here is a screenshot, zoomed in to avoid the PDF viewer from "speeding up" the display by dropping such vital info. Zoom in, do you suddenly see linewights in your own generated PDFs?