OAM 11.1.2.1 -- agent monitoring not functioning properly

Dears,

I was trying to explore the OAM monitoring via OAM console as per Monitoring Performance by Using Oracle Access Manager Console - 11g Release 1 (11.1.1):

For OAM instances: OAM Console -> System Configuration -> Server Instances -> {INSTANCE_NAME} -> Actions -> Monitor

For OAM Agents: OAM Console -> System Configuration -> SSO Agents -> OAM Agents -> highlight {AGENT_NAME} -> Actions -> Monitor

Instance monitoring seems working fine, however I noticed two things:

1- For OAM instance monitoring -> OAM Agents tab; for some agents I'm getting the wrong agent status. For example, an agent with a status "Disconnected", although that agent is working fine. Other agents are not shown at all (although also functioning well)