Opening appears black in 3d view

[dgt.mantis]

I am using Revit 2018.

I have an interior concrete wall that I have cut an opening into to create a balcony over a space below.  See attached images.

I have cut this wall with a wall opening and a door opening.  Both appear black in the 3D view.  I made sure that the door opening family is showing "transparent in: 3d view" yet it is still black, just like the wall opening.  

How do I make these transparent?  Is it a property of the ext wall or what?

Any help would be greatly appreciated as this is really frustrating. 

[dgt.mantis · Accepted solution]

Ugh...after exhausting all options based on the model and families themselves, I went nuclear.

I began turning off individual objects piece by piece in all of the consultants linked models.  While I had already filtered a bunch of this obvious stuff out (like structural walls, MEP, Technology etc.) there was one buried thing that I did not realize was there.

Apparently, for some unknown reason, my MEP engineer had decided to add their own walls (basically generic extrusions) to the "Generic Models" category.  This was the culprit!

Anyway, TL;DR = always check linked model visibility.