Most of the times when publish is not working, the reason is that the user who is publishing (mac- tenantid -replication) doesn't have the latest private key, and hence publish fails with "401 unauthorized" and no other error is reported in replication agent logs. You can avoid troubleshooting and create a new configuration instead. For the new configuration to work properly, clean up the following from AEM Author instance:
Now the system is all cleaned up. You can attempt creating a new cloudservice configuration and still use the already existing JWT application in marketing.adobe.com/developer/applications. there is no need to create a new application, rather just the public key needs to be updated from the newly created cloud config.
Developer connection applications visibility issue
There is one known issue on this UI that for any tenant only top 10 applications are visible. When you create the application, stay on that page and bookmark the URL. You don't need to go to applications listing page and find out the application you created. You can hit this bookmarked URL directly and update or delete the application whenever needed.
To create a new configuration, refer steps to create cloud configuration.