A new Oracle agent is created in the FMS which monitors the instance using a virtual hostname on the database dashboard. The hostname displays the virtual name in the name and hosts column instead of the OS physical hostname.
The OS monitoring also does not work because the OS cannot be connected to using the virtual hostname.
Select monitor OS when creating an Oracle agent for the installer to set the osUsePhysicalHostName=1.
Run the groovy script in KB 233194 to change the parameter 1 for the agent.
Enhancement FOM-1168 has been logged to improve how the Oracle installer handles physical and virtual hostnames in cluster environments. This is planned for a future release of the Oracle cartridge.