Hiding polygon meshes

[dstnwst]

I am having problems with imported vendor supplied blocks (3D) not hiding correctly when plotted. Specifically A-B contactors, terminals and relay mounts. What I have noticed is that they are constructed using lines, polylines and polygon meshes rather than surfaces and solids. Most of the time they play well with others, but I have had 3 drawings where these items tend to want to be seen no matter what I do.
I have attached the latest problem child drawing in a .ZIP file if anyone would care to look at it. WARNING... If you try to plot it, make sure your Shade Plot is set to "hidden" (not "3D hidden") and you set dispsilh to 1. Otherwise it takes about 20 minutes to process the plot. By the way, it plots correctly when set to "3D hidden", but like I said it takes forever so that is not a viable option.

[RenataP]

When I use blocks from AB, which are 3D even when you select the 2D, I end up taking a snapshot in the 3d world that flattens it into a 2d view and that takes care of the problems for me.
Here is a small example attached: