We are using Shave in combination with the new VrayMtlHair3. The VrayMtlHair3 material does not seem to have an option for adding a material ID (or any other vray attributes). Is there any way to get it to work with a multimatte pass? Will future versions of the VrayMtlHair3 have a material ID option?
You can use Material Select Render Element to extract the VrayMtlHair3 in separate pass.