When creating jobs with ProjectBuilder no error is thrown at build/deploy time if a project listed in jobs/job.xml doesn't exist. Instead, JobCenter simply displays an "n unauthorized jobs are not shown" error where n is at least the number of jobs with an undefined project.
I experienced this bug with ControlTier version 3.4.12 when attempting to load the "Who" job defined at http://controltier.org/wiki/Use_ProjectBuilder#Define_a_job.
controltier 3.5.x correctly fails to store jobs referencing a project that doesn't exist