When a Light Function material is applied to a light source, and after using a camera position node and plugging that node into the Emissive Color option there is no light being emitted from the light source.
The user had posted this on the forum as well, and another was able to reproduce the same issue. I was also able to reproduce this.
No light is emitted.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-99353 in the post.