You said “GROUND” but your UCX meshs are related to “GROUND_01”, which might explain why it doesn’t work, unless its just an error on your part when you wrote it here. If not, just rename “GROUND” to “GROUND_01” and it should work.
I do think your collisions could be simplied quite a lot, looks like there is too many seperate meshes which could just be one, more simple shape.