Wrong landscape material being baked into map after cook

I’m having a very weird problem. Note that this issue is only very recent, most likely cropping up within the last update or two.

I have modified a landscape material based on “Mat_TheIslandwithMasks” and applied a instance of that to my landscape as well as a hole material based on my modified material. Of course the copy which is the modified version of “Mat_TheIslandwithMasks” and the hole material is in the same folder as my map. Renders perfectly in editor and is perfectly usable.

The issue is this: For some reason when I play the map in game the landscape renders as if it has “Mat_TheIslandwithMasks” applied.

I’ve even tried applying the correct material to each component through the landscape/manage selection tool and still is incorrect. At one point I was using the hole version of “Mat_TheIslandwithMasks” for my hole material so my assumption is that the cook process thinks I have that material applied all over the map, despite not actually using the visibility mask anywhere. I tried fixing this by creating a hole material based on my main landscape material but still hasn’t fixed anything. Perhaps the shaders are compiling still under the assumption that I still have “Mat_TheIslandwithMasks”" applied?
Is there a way for me to force delete all shaders and recompile them again?

Just a update, I deleted my derived data cache and recooked all the shaders (took 12 hours) and still it’s the wrong material.