Hello I just found (12.4) that at least in the map Grainwoods river, there are multiple zones with 2D Rock textures without 3D model or colision.
And in other cases you can found invisible terrain without textures but with collision and 3d model.
Here a map of the zones where I encounter this issue.
By the way KSIVA banished from PTS 12.4
Greetings and keep it improving the game.