roof windows - not appearing in 3D image

I am working on a building that has a number of roof lights

dormer type/ vertical ones.

when I create the vertical part of the roof, I add the windows afterwards.

as I add them, I can clearly seen they have been added in.

the roof outline is in red, the windows in a type of green.

however, when I go to view the 3D image, most of the windows are not shown.

is there an easy fix for this, to make all the windows appear in 3D