I'm testing C3D with an existing project, and I've run into a situation where survey cogos (trees, lightpoles, manholes, etc), while not displyed in 2014, show up when the file is opened in 2018.
Presentation and layer table in 2014:
v2014.JPG
Presentation and layer table in 2018:
v2018.JPG
Did AutoDesk decide to change how "off" affects visibility of layers in a VP? Yes, I know I can just set all of them to frozen, but this isn't the only affected file. There are about 3000 others in the project.