Hello, I am using the newest version of Terrain3D and Assetplacer. Placing assets on the terrain3D does not snap it to the surface correctly, it seems to be jagged/steppy based on the Terrain3D vertex placement. Your documentation asks to "enable Debug Collisions in the Inspector", but I do not see such an option in the current Terrain3D version. 

Debug collisions is only for when you want to use the surface placement mode. It might be that the feature has been removed in newer Terrain3D versions. 

Can you provide a video or animated image showing what you mean by the jagged snapping? It might be intended behavior. Snapping is predominantly designed for flat sections of the terrain.