It may be you have two walls of the same dimensions
in the same place in your model, one with a window
and one without a window. In 3D the window trim
will show but the wrest of the window will be buried
in the second wall. To check this, make a section line
90° to the face of the wall through the window and
see if the section shows any walls, or delete one of
the walls (if there are two) and see if you now show
either one solid wall or one wall with a window in plan
(depending on which of the walls is deleted).
AC will only insert an opening in one of the walls
if two walls co-exist in the same place.
Peter Devlin