Hi Matthew

My next step would be to check the setup for your Post Processor. 

1. Un-tick the 'Auto Marking Settings' and see if you can post.

2. Assuming you can post without marking, go into Setup>Installed Machines, select your machine, select Tools... , your Marking tool and then Setup. Make sure these settings look right to you.

You could try contacting your Autodesk Partner or Autodesk Support directly.

I would normally do a remote session to resolve this sort of problem and charge accordingly.

I'm about to break for the Christmas holidays returning on 13th Jan.