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Ray Tracing/ Light function issue?

I’m not entirely sure if this is in the correct section in the forums but i’ll try here first anyway.

I’m having an issue with some lighting using raytracing. I have raytraced light, shadow and reflections. This is for a cinematic so i’m not aiming at being fully ‘realtime’.

I have a car with some emissive headlights that are controlled in sequencer to turn on via a scalar in a material parameter collection.
This works fine, but obviously emissive materials don’t emit any light to work with raytracing. So i’ve set up some point & spot lights to turn on at the same time as the emissive material and I figured I could make it all controllable from that single scalar that controls the emissive material on the headlights. I leave the intensity of the lights set at their desired final value (20 in this instance) and then I made a light function that uses the emissive scalar value from the parameter collection to turn the light off and on.
This seems to work fine, it turns the lighting itself on and off but even when the function is completely black and ‘not emitting light’ I seem to be getting a reflection from the light based on its intensity value.

In the first image (light function off) you can still see the raytraced reflection of something but no actual emitted light.
In the second image (light function on) you can see the light emitting actual light and lighting the car up.
Both images have the light set to an intensity of 20 but the function in one is black and the function in another is white.

I might be getting the idea of what light functions actually do wrong (I thought they could be used to turn lights on and off e.g. flashing flickering lights) or this might be an actual issue that wouldn’t be noticed in most use cases?

Am I expecting light functions to do something they can’t actually do? It seems they do stop the light emitting but not the reflection which is weird.

I know I could just animate the lights intensity individually but I figured it would be quicker and easier to adjust things over multiple lights if I used the already animated value I had in a light function on all the lights i needed to turn off and on.