Bug Static Collider with Parent

Hi

I have a few static colliders with no collision response under an enity. I am using those colliders for raycast.
I am aware that all physics objects are unparanted in order to take part in the simulation but these colliders seem to stay as children... which is great as this is what i want.

However if i add a rotation to the parent then the children become unparented by the physics system..

Where is the bug?

Is there anything i can do to have raycast colliders only as children?

I am using Unity Physics