I had some problems with shutters showing on my apartment building and what I eventually figured out was that the hidden room markers in the rooms of the NPC apartments were hiding them.
I thought of two work-arounds. Basically, if you want to have shutters on your custom built apartment building (one made not using one of Bridgeport's apartment building shells) then you have a choice to make.
You have to ask yourself which is more important to you, getting to use what ever windows and shutters you want but being able to see the insides of the NPC apartments while playing?
OR...
Using the one window available in build mode that comes with shutters attached (can't be hidden by the room markers) and having the NPC apartments completely hidden.
If you prefer the first option you can just build a tiny 1x1 room right around the inside of the NPC door and drop a hidden room marker and leave the rest of the apartment visible.
You'll probably want to furnish the apartment doing it that way but at least you can use what ever windows and shutters you want.
Or if you're okay with using the the window that comes with shutters already attached then you can go ahead and hide the whole apartment and not have to furnish it.
I figured I'd post this here for any one else that runs into this problem in the future. Hopefully this post will be of some help.
