This is a follow up to EM12cR2 reports Job Purge repository job as Down. Erik at the OTN Forum has provided a fix:
Simply run the following update connected as user SYSMAN on your repository database, and the repository jobs will all show as clear and the open incident will be closed:
UPDATE MGMT_PERFORMANCE_NAMES SET display_name = NULL,
dbms_jobname = NULL, is_dbmsjob = 'N', is_deleted = 'Y'
WHERE UPPER(DBMS_JOBNAME) LIKE 'MGMT_JOB_ENGINE.APPLY_PURGE_POLICIES%';