Tiled2Unity doesn't import map with textures into Unity

I've been trying to fix this for hours now but still can't seem to figure out what's wrong.

Every time I import my tile map into Unity using Tiled2Unity, the map is only loaded with the outline of the map mesh but no textures. I have the texture used located in the 'Art' folders in my Unity project 'Assets'. The textures work fine in Tiled and the 'Preview Map' button on T2U.

How do I fix this?

-Redza