Converting a Terrain Collider to a Dots Collider will not be registered by Raycast

I want to raycast the Terrain. I am using the approach from another thread to create a Unity.Physics.TerreinCollider from a UnityEngine.TerrainCollider. It all seems to work, when it gets converted. But when i want to raycast against it, it never ever returns a hit. Yet differently Converted (Baked) Collider will be hit

Okay after a few days of fiddeling about i found the problem. The filter cannot be Default. The BelongsTo should be Terrain: 0, the Collides with should be everything and the index 0.