Doors not visible in 3D

[DangCad1]

I'm working on a project where the doors are not visible in 3D view or elevation, only the openings. 

They are visible in plan, and the doors are objects from the standard library (not "Empty openings" etc). 
What might be the problem here? See screenshots

   

 

Appreciate any help!

[DangCad1]

Thanks for your reply. As you say, the library menu contains the "missing doors" section (not specifically realted to built-in libraries though) but it's grayed out and I can't click it or get any information about it. 

However, I don't think that's the problem anyway because:

A. When I check Library manager, the only missing object is a zone stamp.
B. If I drag-copy a wall with one of the empty door objects out of the house, the door appears in the wall (see screenshot, red marking is the original wall and blue is the copied).

Rather, there seems to be something interfering with the door objects but I can't figure out what. The walls in questions are trimmed to the roof, but clearing all connections doesn't do a difference. When turning all the layers on, no objects are interfering with the doors in question.

I don't know, maybe we reached a dead-end here? 

[Miha_M]

Eliminate the Trim to Roof (which is some kind of a SEO operation) and try to use the  "Crop to Single Plane Roof..." operation - if it's one or more single plane roof elements you have above. The Trim to Roof command can be tricky if the roof elements don't cover the whole trimmed wall element. I never had any issues with trims and doors though, but worth a try.

[Mahmoud Qenawi]

Yeah I think so ( a dead end ) but pls let’s know if you found the logic behind your case.