Wanted to drop an answer here because I was having similar issues with in-world waypoint markers using the sunsky actor, and came across both this thread and a solution to the problem today.
Here’s what fixed the issue for me, as the post says, the EyeAdaptationInverse function is necessesary to make emissive light sources render properly when using high-intensity lights like the sunsky actor and eye adaptation. Due to how it works, I had to reduce the intensity slightly before hooking it into the eye adaptation inverse node, but it looks as expected afterwards.
