I'm getting incorrect results from the Offsetpolyline function. It works fine without arcs but with arcs I'm getting a variety of errors. See images, the magenta line is what it should be doing. I've confirmed the issue by reducing the offset amount gradually until it was 0.1mm at which point the 004 pattern still had the top vectors offset by 0.25mm, and then setting the offset amount to 0 made it line up.