I’ve made some progress. Turns out, some Actors that were using SceneColor that I know work correctly in their Projects of origin were also displaying this behaviour in my Project. So I decided to create a new Level with nothing in it but a skybox, and test again.
This time, SceneColor worked as expected.
This leads me to believe my issue is with my Post-Processing Volume, or other lighting setup.
I will report back once I’ve located the cause.