Process Scheduler doesn't send mails to some recipients

After PeopleTools 8.51 upgrade you may have issue with scheduled job's not sending mails to some of the users. This is reported as Oracle PeopleSoft bug.

Description of the Issue:
While creating a new run control ID, the Process Definition Distribution List is pulled into the run control as expected.  However, once the run control has been used, followed by the Job Distribution List being modified to add or subtract a user or role, PSJob Definition Distribution List changes do not refresh in the run control at the PSJob Item level (for individual processes within the job) but do refresh only at the Distribution List Level for the parent PSJob.

Solution:
This issue is resolved in PeopleTools 8.53 through bug 13409032.