Cannot open source file BinaryData.h

Answered, recently, here:

However, this aspect leaves me with a question:

I have enabled the BinaryData namespace and included it in the JuceHeader all in the Projucer.

Did you save and re-generate your project in the Projucer? This is where BinaryData.h/.cpp gets updated with the new contents. You don’t have to do anything manual (besides #include “BinaryData.h”) … but you should be sure to renerate after adding a resource in Projucer (and marking it as 'included in Binary Resources") …