Hi Joel H.,
Without a scene file it is difficult to say anything with certainty.
If you check off anything in the material under Attribute Manager>Lines>Types, check out what you get then, from there, switch one after the other back on. Then you know what part caused the “artifacts”. Please note that most check boxes are connected to more adjustments, below in the interface.
If the “artifacts” as well the lines you like to have share the same settings, you might consider to use “selections” to filter this problem.
If that isn’t working for any reasons I’m not aware off, please supply a scene with the problem. I’m happy to check this.
All the best
Sassi