I'm guessing that, after two years, you resolved this issue. However, I had the same problem just today (04/09/2020), and here's what the issue turned out to be: imported categories. Since no one else on this thread touched on this, I wanted to point out another item to check
I had a couple of elevations where some appliances (range hoods, dishwashers, refrigerators) were not showing. In the 3D view, however, they appeared as they were supposed to. After trying various things like VG, making sure that items were assigned to the correct workset, I opened the family file. What I found was that the family was not constructed from Revit solids, but from an imported 3D CAD symbol. Since I hadn't considered this possibility, I didn't look at the Imported Categories tab in VG. When I returned to the model, sure enough, imports were turned off in those views. Turning them back on resolved the issue.
Again, I don't expect this to help the original poster; however, when I googled this problem, this thread was at the top of the list. So I'm hoping that anyone else who ventures here finds this helpful.