I was building a 32/64 universal plugin, so I changed it to the default setting and got the same result.
When running the PlugIn Host from Xcode, I noticed this error:
2015-11-06 17:35:59.287 Plugin Host[29779:2280043] Error loading /Volumes/Home/ray/Library/Audio/Plug-Ins/Components/JuceDemoPlugin.component/Contents/MacOS/JuceDemoPlugin: dlopen(/Volumes/Home/ray/Library/Audio/Plug-Ins/Components/JuceDemoPlugin.component/Contents/MacOS/JuceDemoPlugin, 262): Library not loaded: /System/Library/Frameworks/CoreImage.framework/Versions/A/CoreImage
Referenced from: /Volumes/Home/ray/Library/Audio/Plug-Ins/Components/JuceDemoPlugin.component/Contents/MacOS/JuceDemoPlugin
Reason: image not found
I tried adding CoreImage to be linked in both the plugin and the plugin host, and still get that error.