Lines/Edges appear through other parts in Assembly drawing.
Good day.
I have a problem with Assembly drawings in CREO 10.0. Some lines/edges of parts that have been imported as STEP models show up in an assembly drawing even when behind other parts.

These tubes are heat shrink wraps on cable behind several other parts and...

These are connectors also displaying through several other parts in the assembly.
I've tried the "Import Fix" tool etc., but with no luck.
Any advice will be appreciated.

