There's definitely something funny going on with the _gloss in Max, I don't think it's actually working as its own texture at all, at least it doesn't look that way to me ...
This will show you what i mean, from left to right they are the same model, with the same textures, with minor differences;
LEFT: greyscale _gloss on an the grey channel in an RGB texture,
RIGHT: greyscale _gloss on a texture with only a grey channel,
MIDDLE: AO, Metallic, and Roughness packed into the RGB channels of a _SURFACE texture
all textures are from the same source images and simply packed into their respective sets.
Note how the two _gloss models aren't reflective at all, but the _surface one looks awesome. I have a feeling that the individual _gloss texture isn't hooked up yet.
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