Switch to a new certifier doesn't work with CA process

Does anybody have an idea why the change of the certifier for a user not works with the CA process?

I selected the user under People and Groups inside the Admin client, started Rename and selected the option Request Move to new Certifier.

I selected at first the old certifier and within the next dialog the new one. I got no error and also no error information inside the logs of the server.

Thanks in advance for your help!