For now, the user must use pgup and pgdw. This is a problem I found also in the objects created by TGC.
The objects are automatically positioned one above the other only if they are filled solids, for example a cube.
I sincerely hope that this problem will be solved as soon as possible and it is added snap in height. A good reference point for the positioning of objects is axisgamefacory. Objects behave in an intelligent and understand where they need to be placed
Forgive my English
The software I use? ... Autocad, sketchup, Spazio3D, pconplanner, Kerkythea, wing3d, paint.net.