I also was able to get JellyMesh’s solution to work using the world hit check box for physical materials and then a soft object reference in the filter instead of the substring. I actually like this layout better as dropping the material in directly like that prevents the possibility of any spelling errors and makes changing them out much more straight forward.
Another nice bonus for using the world hit like this is that if you combine it with a water body distinguishing between your water body and landscape happens at the physical material filter level so you don’t need to do anything special.
I imagine this soft path thing might also be useful if you’ve got something in your landscape like a big static mesh. I bet you can use it to do something with that.