I have not done much playing with layers, mostly things are just on whatever layer ArchiCAD puts them on, when you build them...
But this problem is not associated with the roof, or the eave...
This issue, as I have stated, appears on all kinds of walls. Foundation walls, wood walls, simple profiles, complex profiles, basement floor, top floor..
There is no roof or eave attached to the basement walls, yet they display this bug.