Some furniture not showing in 3d view

[SpicSpan771]

I am having an issue with some furniture, especially staircases, showing on my floor plan but not in the 3d view. I have already placed doors, windows, and they are showing just fine. When the staircase issue started I tested other furniture, e.g., cabinets, chairs, bed, and they showed up on 3d just fine.

[Puybaret]

If you use more than a level, maybe you should select 3D view > Display all levels menu item. But I'm not sure because you speak about staircases. Where did you get these staircases from?