Light function material has no effect

I am trying to create a TV Glow Effect.

I am using this tutorial -

Starting a new project I can get it to work perfectly as described, however when using an existing set from the marketplace and it doesn’t work (I’m using “Christmas Room”).

The method described applies a Light function Material to a spotlight. I can set up the material to apply to the light using a ScreenCapture2D camera. This all seems to work fine. As I play the video the material updates in the content browser, but the projected light does not change and is just white.

As I say, when using a brand new project this all works fine.

Can anyone think of a setting in my purchased set that would cause this behavior.

I have no plugins enabled.