Ok, so not sure if this is maya or vray, but only seen this with 5.2 update.
I’ve attached scene and video, basically if i duplicate the material that has vray layer and vray correction assigned, the duplicate no longer is connected. It probably some corruption in the scene because if i import into a new one, its fine. But i thought i would send it anyway in case it helps.
dup material.zip (468 KB)
Works fine on my end; tested with 5.2 and 5.1.2. Which Maya version are you using?
Using maya 2022.1.
Odd. Does it happen with every shading network? Have you tried it with f.e. an Arnold one? Or with V-Ray disabled?
no 
its one of those really odd things, like i said I only posted it in case it might be useful. I’ve not seen it happen before updating to 5.2, but it could well be something maya related…i recreated the material and thats fine..but you see what happened in the video…maybe my machine is cursed