I’m creating something where the scene is inside a cube (with the front face missing), the reason is that I wanted to then put the main lights outside the cube and have that shining in through holes which I was going to put in the faces. However if I select the cube and subdivide it, not all the faces subdivide, and if I select one of the faces and subdivide just that…it doesn’t. Not sure what I’m doing wrong here and I’ve run out of ideas!
If seeing the piece would help then the .blend file is available from this link
I’m just learning Blender, but I think you have to be in a view mode where the back faces are visible to affect them. In short, I believe that Blender will let you affect/select only what you can see.
it probably wasn’t subdividing because it was a weird Ngon at that point, notice in face select generally the black square is in the center of the face and for those top and side wall they black square was near one of the edges, to fix you can delete those and extrude the edges of the subdivided sides to recreate them. Then loop cut to finish the subdivision You have some random vertices floating around also.