Attempting to change the agent group assigned in the Agent Overview screen and not all groups defined are listed:
If the agent was originally assigned a Group with the Group Conditions: User Attributes, it will not list the agent groups created with Group Conditions: Endpoint Server.
Release : 15.8 MP3
This is working as designed. An agent group can only be changed to another agent group with the same Group Conditions: User Attributes or Endpoint Server
Define each agent group based on User Attributes or Endpoint Server. Once an agent has been assigned to a Agent Group/User Attributes, only the agent groups defined by user attributes will be listed.
https://techdocs.broadcom.com/us/en/symantec-security-software/information-security/data-loss-prevention/15-8/about-discovering-and-preventing-data-loss-on-endp-v98548126-d294e27/overview-of-the-agent-group-deployment-process-v97217467-d228e67.html