The health issue that may be detected is a lease time-out, and the SQL Server error log will display the following text some time after the stalled dispatcher is reported:
2014-05-30 10:30:50.19 Server The lease between availability group 'TFSAG001' and the Windows Server Failover Cluster has expired. A connectivity issue occurred between the instance of SQL Server and the Windows Server Failover Cluster. To determine whether the availability group is failing over correctly, check the corresponding availability group resource in the Windows Server Failover Cluster.
Service pack informationTo fix this issue, get Service Pack 3 for SQL Server 2012.
bugs that are fixed in SQL Server 2012 Service Pack 3 .
Cumulative update informationThis problem was first fixed in the following cumulative update for SQL Server:
Article ID: 3081074 - Last Review: 23 Nov 2015 - Revision: 1