We have been having this issue for years, and it has stumped any Autodesk tech we have spoken with. It seems to have some association with the viewbase command, and it causes anything in paper space to print in grayscale, except for the hidden line layer created by the viewbase command. That prints in blue, which is the color we use for a hidden line. a viewport looking directly at an isometric of the model also prints in color, as it should.
These are typically also created in Plant 3D, going back to 2010, which is about when we initially saw this issue.
I have attached a pdf of the most current drawing. If anyone has any ideas, we would be very appreciative. Thanks.
Phil
