Header Search Paths: Project VS Exporter

This is probably an amateur question, but I haven’t been able to find a definitive answer.
How do the general header search paths for a given JUCE project (Seen by clicking the gear in the top left next to the project name) differ from the specific header search paths tied to the debug and release versions of each exporter?

I would imagine the exporter specific ones are only used with said exporter, but there seem to be other underlying differences I don’t understand. For my current project, I’m using Nlohmann’s JSON parser. When I include the directory in the general project header search path, it fails to compile, saying it cannot find the library in question. If I move all my paths to the exporter specific header search path box, everything works without any changes to my code (or the paths themselves).

What am I missing here?

I’d have thought they’d be added together!

Have a look in your IDE for the result and see what it’s getting from Projucer?