Hide foreground/view background only?

I've been restoring this abandoned underground dungeon/castle and trying to colonize it. However, the colony deed keeps saying that it's unsuitable for tenants. I've looked everywhere for holes, I've run through every hallway and tried placing background blocks behind every foreground block, but still no tenants. It's a very large space so I'm thinking I just have one background block missing behind some walls that's messing things up. Is it possible at all to hide/make invisible the foreground? that way I'd be able to see for sure if it's because of something missing in the background as opposed to everything else. The building has doors, lights, and decor, and the foreground walls are sealed as far as I can tell.

 

The only thing I can think of without a pic, is that it could be too big. There is a limit in how small and how big an area must be in order for the device to register it being livable. Also it could be certain furniture not mixing well. That is to say not all combinations work. Could try the basic minimal of things. Yes having light, door, and 2-3 objects work, but it is the objects that one must choose carefully in order for it to function.

That is about all I could think of, as you mention having filled the space of foreground and background blocks...

You can have more than 2-3 objects, it is just something to test whether the room works for the size of it...

 

O.M.G. thank you so much, you were right it was too big! I sectioned rooms off with doors and it worked like a charm