Vray toon with Vray override material question

[windrockwater]

So I am trying some renders using a vraylightmtl in the vray override mtl slot. And then i put vraydirt in the slot for the vraylightmtl. I then render with the Vray toon atmosphere effect enabled. It looks great BUT plants that have opacity mapped leaves no longer render as they should because it renders the face of the leaves for some reason that I do not understand.

Does anyone know a workaround for this?

[windrockwater]

Is this becuase ALL materials are being overridden so opacity mapped materials simply cannot work with an Overridemtl active?