On most PC shaders, when Audio Link is set to control the emission, the emission is set to off when Audio Link is not in a world. for Toon Standard, the emission is set to full when audio link is not in a world. The emission should be overridden to off when audio link is not present in a world and audio link has been set to use the emission mask. This could also be an option in the shader, like a check box, so as to not break current logic that already gets around this issue.