I’m around, so just reply to the thread or whatever.
As far as diagnostics, the best method is generally to work backwards.
Skip the rock material, and use a color like red [1,0,0]. Hold 3 and click into the material graph, and then use that single color as your base material. Blend with that with the rvt and see what goes where. The alpha is going to be your focus since it determines what shows up where.
Otherwise, it’s a step-by-step process to take what works and then add 1 thing, then one more. Eventually it will break and you can focus on that thing.
Check this guy out, he’s where I started learning all about unreal materials. He has a multi-part series on landscape stuff: Landscape Material Tutorial Part 1 (Unreal Engine 4) - YouTube