One thought occurs to me, I can't recall the circumstances, but I recall a similar problem regarding ground textures - i think I solved it sizing and superimposing a one-sided square on the ground plane - applied the texture to THAT, instead of the ground plane itself - all worked okay after that - seemed to me the ground plane is sometimes more a virtual reference than an actual object - don't know why. Hope your problem disappears - I find the environments from Graphons Elite Expressions site absolutely invaluable for a lot of my projects. Good luck