Most likely the problem is that you use Width / Height (pixels) not 256 * N.
At this size, all methods of converting coordinates to Unity World Points and vise versa do not work correctly.
This is a known problem, and we'll fix it in future versions.
But this problem is very "deep," and it's very difficult to fix it.

Work around for this problem is very simple - use the size (Width / Height (pixels)) = 256 * N.

There is some incorrect correlation with coordinates and 3D Buildings.

As you can see in attachments, they overlap the streets. I'm on 5.6.0f1 running in the Editor.

How can I can workaround this?