When I apply meatless to my aiStandard it looks great in my material viewer but looks black in my viewport. Is there a way to solve this? It look SOLID black in my viewport. Thanks.
This is technically correct, when metalness is at 1 you don't have any diffuse hence the black color. If you tumble in the view and have some lights however at some angles you can see the specular reflection. I agree it's not really pleasant to look at and probably some little tweaks could be adopted to have the material 'almost black' instead. Same goes if you have full transparency .. the material just disappear 🙂 You can mitigate a bit on your own this by using a second material just for vp by plugging the original mat into the Arnold SG slot and the one you plan to use for the vp in the Surface material slot.
What software are you using? Maya already has a pretty decent representation, can't say for others, you can add a skydome with an HDRI and it will help you visualize both metalness and roughness.
