How to use existing STB file?

[stuart-willcocks]

I'm having difficulty applying an existing STB file using ezdxf so that it affects the visual style of an exported PDF.

My workflow is as follows:

INITIAL CREATION

1. create generic drawing in AutoCAD, with plot style controlled by an existing STB file. The plot styles work correctly if I export a PDF directly from AutoCAD.

2. save drawing as dxf (version 2018).

PROCESSING USING EZDXF

1. load STB file as follows:

stb_path = r"C:\\Users\\xxx\\AppData\\Roaming\\Autodesk\\AutoCAD 2024\\R24.3\\enu\\Plotters\\Plot Styles\\plotstyles001.stb"
plotstyletable = ezdxf.addons.acadctb.load(stb_path)

2. load DXF file created above:

doc = ezdxf.readfile("C:\\_repos\\drawings\\myfile.dxf")

3. apply plot style table to both modelspace and paperspace:

msp.plot_style = plotstyletable
psp.plot_style = plotstyletable

4. set layer visibility and text attributes (this all works fine)

5. export PDF as follows:

pdf_bytes = backend.get_pdf_bytes(page)
with open("plotstyles.pdf", "wb") as fp:
	fp.write(pdf_bytes)

The PDF is created, but the plot styles appear to be ignored. Is there anything fundamental I'm doing wrong here?