Hi,
The most likely cause of this kind of error is clashes in the model. If there are clashes anywhere in the model, even small ones nowhere near the part in question, it can confuse the drawing engine and lead to incorrect linetypes being used in places. In practice tiny clashes rarely cause a problem but any noticeable clash is likely to cause an issue somewhere. The only way to be sure is to fix all clashes (soft clashes for tool diameter around bolts do not count for this). Then try updating or regenerating the drawings.
If you are using Advance Steel on Advance CAD you can also try changing the Modeller setting in Defaults. GO to Management Tools > Defaults > System > Modeller. This has a choice of Autodesk or Graitec modeller. Whichever it is set to try the other one, reload settings / update defaults, and regenerate your drawings (rather than update). This may often make a difference too.
Regards,
Aleck.