Why?
I am working in a project that we upgraded from 2012 to 2013. In 2012, I had filters set up to show a piece of the Architectural link (a generic model; elevated seating slabs) would show as solid linework in my sections.
Basically,
In 2013, the Underlay feature seems to have an additional "feature" that is unwanted. When I set the Architectural link to Underlay, it does send the file under my structural model, but it also makes the underlay HALFTONE! So, I cannot get that piece of generic model to show solid. Why have the additional Halftone checkbox if the Underlay is going to do that anyway?
I also tried with a new 2013 project template, linking the same Architectural model and cutting the same section. When I set the link to underlay, it turns halftone, too! Also, tried changing from Structural to Coordination with no change.
UPDATE:
To turn off automatic Halftoning of the Underlay feature, go to
Manage Tab > Settings Panel > Additional Settings pulldown > Halftone / Underlay dialog box
and uncheck the "Apply Halftone" checkbox.