After doing some research this could be related to a bug recently discovered where we do not completely unload one of the agent libraries.
based on information I found you may be able to access the agent CLI on the DB server and do a stop/start.
Stopping the agent from the CLI stops all agent processes - stopping the agent form the UI only stops the ragent process
This was just recently discovered in our QA testing
The bug is associated with these bug-IDs - AGNT-10224 and AGNT-10711