I'm not able to see metrics in OC, I have noticed that ci_metric_id's are not written to the DB and I have overall Discovery_server issues.
Looking at the discovery_server.log I'm seeing the following error:
Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: The connection to the host "NamesInstance", named instance CAUIM failed. Error: "java.net.SocketTimeoutException: Receive timed out". Verify the server and instance names and check that no firewall is blocking UDP traffic to port 1434. For SQL Server 2005 or later, verify that the SQL Server Browser Service is running on the host.
Release : discovery_server 20.4
Wrong server name defined in the data_engine
Database Server Hostname or IP
Database Server hostname or IP address. If you have selected IPv6 installation environment, then enter the IPv6 address as the database server hostname.
Remove the instance name from the Server key in the data_engine.
And restart the data_engine