Landscape Black When Applying Landscape Material

Development World Creation
1

For some reason if I try to apply a landscape material from any pack I’ve picked up for the marketplace my landscape always ends up this weird shiny black.

I can apply the Landscape Auto Material just fine but a material from any other pack will not show.

Any ideas?

And for reference I wanted to try and use the landscape material from this:

2

Same this also happened to me, not sure how to fix this.