I noted something very similar to your problem, Owl, concerning studio's occasional inability to read random/legacy mat5 and mc6 files, but they work fine if you were to manually change the file extension to pz2. It was found to be a confirmed flaw after Mr. Haseltine informed me to submit it through the bug tracker. It's there with ds4 and even ds4.5 apparently (I don't have 4.5 as it came out while I was on vacation. Oh well)

Add: I reread your second post about items that don't change textures/mats, but the colors do change. Sometimes this could be confused with a shader effect rather than a texture or mat pose. I couldn't begin to tell you all of them, but there are a great number of shaders that, in my experience, actually can be used to 'stack' an effect on top of a mat pose. You might not notice a big change until you render them. One I've noticed in particular that has more of a layered or stacked shader effect is Cloth FX. I'm still trying to find where it came from, but it was a freebie and one you can use to turn a material into either a leather or spandex look.

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