Collision of Child of RootComp not recognized

So I don’t know what happened here but it once worked and at some point it stopped working and now I noticed (too late).

I have a ACar which has a collision comp structure like this.

At runtime I attach another StaticMesh with a collision material assigned to it and a UCX collision body.

grafik

This is the final car in game:

In the project settings I have these set up:

Problem: Only the RootComponent ever collides with something. But when I set up the other collision components so they could potentially collide with the boxcomponent the car simply flies around.

Edit: the ground meshes have the profile “Ground” assigned and the wall meshes have “Wall” assigned. So the only thing that works is wall to car->RootComponent collision. Everything else is ignored.