Why is Measure Length giving me an inaccurate length?

Has anyone found a reason for this occurrence (or how to make it stop)?? This persists in 10.10.21.4 and has caused some issues with our production staff, especially with drainage pipes that are 3D modeled. My theory is that it is caused when an element has a 3D representation for its profile (a construction element) and the tool is calculating both. But who knows?? 

Has anyone found a reason for this occurrence (or how to make it stop)?? This persists in 10.10.21.4 and has caused some issues with our production staff, especially with drainage pipes that are 3D modeled. My theory is that it is caused when an element has a 3D representation for its profile (a construction element) and the tool is calculating both. But who knows?? 

Doesn't seem to be clear why this core MS tool treats drainage conduit differently.  All I can suggest is to have them utilize a Civil Label (text fav) named something like "Conduit Run Length" or "Pipe Measure Length" and train users to use that (ProTIP: or add a GUI button).  I know, not ideal as it bulks up the file (drainage files already bloat quickly-right!), however those checks can be done in a separate review file.