Hi Alex,
There is a new way for Rhino 8, that appears to be being used successfully.
The Rhino 8 way which is different than previous versions, is to make a Linetype definition and set it to use Model units See the discussion in this related tread here..
The linetype needs to be set to “use model units.” And the Print options do not do anything. They will likely be removed for this reason. The developers have the issue. I do not know if the Print option will stay and not work, or just be removed.
Give it a try and let us know if you still have issue.
You can email a file to tech@mcneel.com attn Mary if you need additional help.
Sincerely,
Mary Ann Fugier