I recently deployed 6 callbridges and 5 database nodes of Cisco Meeting Sever.
One CallBridge displays in the Configuration > Cluster, the status of "Connection attempted" to other callbridges, while in the Event Log, I seen the connection from this callbridge to other callbridges is successfull.
To solve the issue, remove the callbridges from the Cluster API configuration then reconfigure the call bridge connection in each call bridge.