Substance painter 3d metallic material not rendering in Arnold

Hello,

I'm trying to texture a character with Substance Painter 3D - I've been having issues with rendering my textures in Arnold with Maya. The metallic texture shown in Substance isn't appearing in Arnold - I have the metallic node plugged in, set to raw color space and alpha as luminance is checked, there's also an HDRI illuminating the scene so I don't think it's a lighting issue. \

Any ideas?