Confused by PostProcessing, cannot get my settings to work?

Hello Andrew.

Yes I’ve tried rebuilding lighting (on all qualities).
No the settings were not tried at the same time.

I’ve made a New Project and confirmed that what I’m doing is correct - it works in the new project.
I’ve made a new level in the problem project, and the Scene Color change is ignored. I think we can safely say that something in the problem project is broken, but I don’t know where to look.

Thanks for your help!