I am using the Bézier Path Creator asset and its Road Mesh Creator to programmatically generate a race track and surrounding surfaces (grass, gravel, pavement). As you can see in the screenshot below, the pavement material is rendering properly, the gravel and grass are just solid colors.
All three are 100x100 png textures with the same sort of pixelated appearance. The materials are Unlit/Texture and Tiling 1x100. I have set the Render Queue in order to get them layered properly (grass - geometry 2000, gravel - geometry+1 2001, pavement - geometry+2 2002).
I’m not sure what other information will be useful. Just ask for more details if needed.