If you are planning to upgrade your OEM to 188.8.131.52 and you have RMAN jobs scheduled in Cloud Control, you should consider applying patch 19519190 to the OMS. I noticed that most of the RMAN jobs were having issues and even worst, some steps were empty!!!
Obviously, the jobs were succeeding as the step is empty. In other words, the jobs were doing nothing.
Looks like this patch is not part of any PSU, yet! But having a problem with hundreds of jobs and especially with RMAN jobs is very risky.
Take a look at EM 12c: RMAN Step Commands are Being Removed from Multi-step RMAN Script Jobs in Enterprise Manager 184.108.40.206 Cloud Control (Doc ID 1914916.1).