Just a question regarding manual failovers. Does it matter if we use SSMS to perform the failover vs going to the Failover Cluster Manager and move the role to the secondary node? Is there a preferred method or either one is fine to do?
Do not use the Failover Cluster Manager to move availability groups to different nodes or to fail over availability groups. The Failover Cluster Manager is not aware of the synchronization status of the availability replicas, and doing so can lead to extended downtime. You must use Transact-SQL or SQL Server Management Studio.
Complimenting to Tara's answer ... You should tsql / powershell for availablity group failover.
ALTER AVAILABILITY GROUP MyAg FAILOVER;
You should check
sys.dm_hadr_database_replica_cluster_states dmv to see if the replica is ready for failover and there wont be any data loss.