Applications Manager Queues can be activated and deactivated at any time. Just like Queues, an Agent can be Stopped or Started at anytime.
Sporadically these functions fail to respond when trying to activate/deactivate or Stopped/Started.
In most cases, this is due to a configuration with Applications Manager and a load balance set up in Oracle such Oracle RAC or SCAN RAC
Component : APPLICATIONS MANAGER
Applications Manager does NOT support load balancing or an configuration where Applications Manager is not strictly connecting to only one specific database node.
In any multinode configuration, it is recommended to disable load balancing.