Closed Colony limit?

I was wondering if its how i set up my colony or if i hit the max limit (which shouldn't exist). But my new houses/or apartments doesn't want to register anymore npc. Here's some picture of how the structure it.

Bottom:
https://gyazo.com/230434c16c17bed32648fe83ef7d4687

Left:
https://gyazo.com/51a92e7953957aa72a22a8599de9872b

Right:
https://gyazo.com/7af5e814b498a03c8a7c42438d16678e

P.s. i did block the top platform after these pictures.