12.5 is a ways back, but, I think some of the bugs regarding this have been fixed even in that version.
It does take a little bit of time for Jabber to refresh that tab and reconnect. Can you check the Jabber log and/or firewalling/tunneling that it is able to access the Unity Connection server's VMREST service? I think it also uses Jetty for web socket. If it overloads or isn't able to connect it will fail over to the other server configured in the service profile, but there is some time for this.
I had an issue with that with the Expressway that were was a problem with Unity Connection and the 400-class errors coming back from the API annoyed the Expressway enough to have fail2ban block the client.
But yes in the past with Jabber there were instances that it would just not refresh or would sit there, if you can try a later build and it works then that is an easy answer.