SQL Server - Kerberos Configuration Manager - Unable to connect

Hello all -

I am currently working through replacing a development and production SQL server, moving from server 2012 to server 2022.

These two servers have the SQL Service running as an AD account. Thus, I have gone through and configured the proper SPNs in Active Directory and configured Kerberos Constrained Delegation.

Adding the SPN for the FQDN and hostname, with and without port (1433), on the AD account the SQL Service is running under. Going to the delegation tab for that user account and adding the MSSQLSVC<hostname> and MSSQL<FQDN> with and without port. Going to the AD Computer object of each of the two servers, to the delegation tab and adding the server that I am looking for these two servers to access via a cifs share.

When I login to SSMS from my PC to connect to these servers and run the query:

use master

GO

SELECT COUNT(auth_scheme) as sessions_count, net_transport, auth_scheme
FROM sys.dm_exec_connections
GROUP BY net_transport, auth_scheme

I can see that the my TCP connection has an auth_scheme as KERBEROS.

However, when I try to launch the Kerberos Configuration Manager and try to connect to the local host (leaving the server name, use name, and password blank - while on the server as an admin) - I get the following:

"Unable to connect to server, please ensure that the server name is correct, SQL Server is installed properly, and the user has administrator permissions. If the problem persists, please contact Microsoft Support."

I am an administrator on the server, ran the application as administrator. I'm not really sure where to look from here. Any help or tips would be appreciated.

Thanks

Steve