Organization Page Background Color being ignored

I’m setting “Page Background Color” in my organization settings but it’s having no effect on the background color in my new universal login experience. If I don’t log in to an organization then the background color correctly uses the setting from Branding > Universal Login > Page Background. But when logging in to an organization it’s always black, no matter what the organization setting is. Changing the “Primary Color” for an organization does update the button color but the background color setting does nothing.
Any ideas? Thanks!