We noted that the End User Notification Agent was showing an older version in Manage > Computers on the Plug-in Versions tab of some computers.
The Software Update Plug-in upgrade policy was stalled or not enabled. The End User Notification Agent is a part of the Software Update Plug-in (Patch).
Release: 8.5 RU2 and higher
In this case, we changed the Software Update Plug-in Upgrade policy schedule from the default of Run Once ASAP to having two schedules as seen below:
For information on this agent, see Using the new End User Notification Task in 8.5 RU2