Custom Terrain Material Won't load

So im having a go at map creation, im about a day and a half in...with that being said I am a complete noob with map creation, most of the stuff was quite straight forward but ive been having issues with materials all day long...4 and a half hours of frustration. No matter how I set the materials file, my material doesn't show up in the terrain material painter. its beyond frustrating considering there isn't much documentation about how to correctly do so. Thanks for looking at this.

MATERIALS IN THE EDITOR MATERIALS FILE
(top material is mine)

MAP "FOLDER"
------> levels/Deriphill/art/terrain/ -->main.materials.json

 

Still having this problem, does anyone have any suggestions?

 

just ping Nadeox. This looks like something they can handle better than I can.