RESOLUTION--- restarting the discovery_agent resolved the issue.
Useful info: User Tags are stored in the CM_NIMBUS_ROBOT table and the responsible for the correlation between the robot and the DB is the discovery_server. Please check if your tags appear correctly in this table. If not, do the following:
1. change the User tag on the robots on which it appears incorrect in the DB
2. restart the robot only 1 time
3. deactivate discovery server, then activate it again
4. wait about 15 minutes, then check to see if CM_NIMBUS_ROBOT was updated.