Wow, this bug took forever to track down!
It’s fixed now. You can update to the newest tip and re-build the Projucer. If you have the DLL (JUCECompileEngine.dylib), you should now be able to live-build again with that Projucer.
The fix will also be rolled out to the website download version as soon as possible (not today though, that process unfortunately takes a bit longer).