Just updated to stables and now I cannot get a good build of my iOS solution. The same source works fine on Xam Studio 5.8.3, it's something with the new stables today. The error is:
/Library/Frameworks/Mono.framework/External/xbuild/Xamarin/iOS/Xamarin.iOS.Common.targets: Error: Error executing tool '/Applications/Xcode.app/Contents/Developer/usr/bin/ibtool': Argument cannot be null.
Parameter name: unformatted (APDL.iOS)