Build Error: undefined class 'juce::JUCE_API

I have weirdness, I created a new audio plugin project, built with nothing but boiler plate and it built fine. I moved over some old files and this happened.

1>C:\Developer\JUCE-7.0.8\modules\juce_audio_basics\buffers\juce_AudioDataConverters.h(35,17): error C2079: ‘AudioData’ uses undefined class ‘juce::JUCE_API’ (compiling source file …..\JuceLibraryCode\include_juce_audio_devices.cpp)

There a few build errors but that’s the first, has anyone ever had that before? It’s practically a mirror image of the original project which builds fine.

Edit: I haven’t fixed it but I can get around it by leaving all files loose in the Source folder. The problem arises when I place files in their own folders and edit header search paths in the projucer.