For this project we're using Autocad 2012, Autoplant V8I (SS4) 2012 and Navisworks 2015. Until we upgraded Navisworks from 2012 to 2015 everything worked fine.
Now half of the time I can open a DWG ( or an NWF) in Navisworks and everything displays as usual, but when I start working, i.e. open the DWG in Autocad, do something, save it and then refresh Navisworks to check, all Autoplant entties are only shown by their boundary boxes, similar to when a wrong object enabler is loaded. At this point, using the 2012 version from Navisworks works OK. After closing Autocad and refreshing Navisworks the Autoplant entities are displayed normally again.
Sometimes I get the problem on the initial opening in Navisworks, changing enabler from 2012 to 2011 or 2013 can fix the problem, sometimes changing the render type from shaded to rendered and back fixes the problem.

What am I missing here.