I found with some old textures (especially for props or hair) the MAT files applied as poses while in the material room do work but the effect is an all-white.    Upon checking everything is in its place but then I discovered a tiny detail - transluscence was to blame as for some reason it was set high and white.   Eliminate that and you should be ok.   It is tedious though to keep doing it for every Mat you apply.  Fortunately this happens to me only with very few items.