mesh display order and building material not working on sections

[KornelSziklai]

Dear Communitiy, I have been working with ArchiCAD since version 6.0, and since we can move objects and overlapping surfaces in sections, I've only now encountered a problem in v26. 
In sections, the overlapping surfaces of walls, girders or slabs do not respond to either bring to front /bring to back commands if they overlap with mesh structures. Eg. if you have a mesh as terrain and you have walls or slab for foundations, the mesh always comes to the top in the display order in sections, hiding the walls and the slabs, no matter how weak its building material is set to, or if I use the bring to front/back commands. This problem was not present in v.25, only in v26. Is there a new tool that I am not aware of or is this some sort of a bug? 
The only way to show such foundations in the terrain is with boolean functions, but that unnecessarily comlpicates the model. 
Please adise, thanks, 

Kornél Sziklai, architect, Hungary/Germany

[sayon3d]

Yep, that's a bug, and a quiet annoying one.

[Oleksandra Vakariuk]

Dear @KornelSziklai,

Thank you for raising this topic!

In Archicad 25 and before, when two elements overlap in sections, Archicad decides randomly which element should be brought up to the front. You can play with element position (Send to Back or Bring to Front) to adjust this, but this action has always been considered unreliable/incorrect modeling. Such a model can produce artifacts with linework and random polygon ordering.
Technically you could change the display order of elements on sections to correct these in 25, but this had to be done per viewpoint and didn't work in Teamwork (since this action is not shared in a Teamwork Project). The display order in Archicad 25 and before also caused a lot of instabilities in different tests which is why the logic behind it has been changed.
From Archicad 26, the display order does not work on the overlapping 3D elements in sections and needs to be adjusted with a proper junction. For example, using a Solid Element Operation.

Kind Regards,