Base with underearth levels as blueprint

i have added several subterrean levels - for hidden rooms - to a base ona kua and then created a blueprint of it. When i use the fabric and spawn it at a new place , the selection cube is all above earth and the base is placed floating in the air, with the lowest basement level just touching the surface. Lokks like it can not REMEMBER how deep to go for proper placement. Is this a bug or can it be done.

Btw, it would be nice to see some wireframe of the spawning object BEFORE placing it...

Base with underearth levels as blueprint