Nevermind, I think I get it now.
Here's your problem:
Brick ownership is saved from the bottom brick upward. So, if you have six bricks built on top of each other with the bottom one placed by you and the other five placed by me, only your ownership is saved because your brick was on the bottom. So when the save is loaded, all six bricks load as if they are all your's.
That's what's happening when you save the bricks. They are being loaded as public because they were built on top of terrain was set as public.
I wish that I could get you a fix for it, but I can't. Ephialtes has at some point made a per-brick ownership save/loader for RTB hosting, but since RTB's been shut down, it probably can't be retrieved now.