UIM - UMP_ADMINCONSOLE
First please verify content of file excluded_devices.csv in the discovery server probe folder. If device for which you are seeing 'No metrics available' in the USM is included in this file, it will not be monitored.
Probably, the entry got added in this file because while deleting any device from USM inventory, we get an option to uncheck 'Prevent rediscovery' . If the device is deleted with this option checked it will not be available for rediscovery. - This is why were unable to see metrics in the USM.
To remove this configuration execute:
1. Deactivate discovery_server probe
2. Remove device from the list
3. Activate discovery_server probe