ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME does not work

I'm using Xcode 12.

I have set the ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME to "AccentColor", and created a Color Set named "AccentColor". When run I still see the default system blue color as the tint.

I don't understand why this does not work. I've done exactly as it is when I create a new iOS project from scratch. This does not seem to work in my existing project.