Examine the fast-start failover configuration:

A failover may occur if the observer has lost connectivity to the primary database, even if the Fast-Start Failover target standby database has a good connection to the primary database

If South_Sales develops a problem and cannot be the target of a failover, the broker automatically changes the fast-start failover target to one of the other candidate targets.

The observer will initiate a failover when the primary database is unable to produce local archived redo log files.

You must disable fast-start failover first to change the fast-start failover target to East sales.

The observer is running.