Vertex Painted Emissive Material Issue (UE5-0)

I’ve encountered an issue when building the light using a master material that blends between emissive ceiling tiles with simple ceiling tiles. After the bake, I still get the lighting from the areas where the emissive tiles were before the vertex paint.
Is this supposed to happen, or am I just complicating the issue by using a material to control my lights, instead of simple planes with emissive??