Unable to kill session in a pluggable database

I have a RAC pluggable database (12c).  The application runs packages/procedures using dbms_scheduler to create and run scheduled jobs.  Sometimes, the dba_scheduler_running_jobs view does not show any running job but there is a session running  (this has occurred in multiple non-prod environments both CDB and nonCDB).  If we try to stop using dbms_scheduler.stop_job we get unknown job error.   Our work around at the moment is to kill the "rogue" job session.  We need to work on this issue, but we are now using a PDB in Dev to do this testing.  In the PDB, I am connecting as a common