I’m having issues with interoperability between Rhino and AutoCAD. The latest problem being polylines exported from Rhino as “Polylines” are being read as “2D Polylines”, which makes them more difficult to edit - some properties don’t appear the same in 2d polyline as they would in regular polylines.
As mentioned here it can be fixed by running a “pedit” command in autocad, however it requires postprocessing in autocad, which may require learning how to write autocad plugins, which I hoped to avoid.
EDIT: Pedit didn’t work on multiple polylines. See the solution below.