Has any of your build or deployment steps stopped working without rhyme or reason? The culprit just might be the Mac App Store (MAS). If you got any of the build tools from MAS (which, granted, probably happens rarely) and you happen to be logged out of MAS, then OS X kindly makes sure that the tool will quietly fail. Say you expected this tool to fill a textfile: what you'll actually get is an empty file.

The fix? Manually launch the mentioned tool and login into MAS with your Apple ID. Obviously, it might take a while before one realizes that the tool's CLI isn't working because of MAS, of all things.