For databases utilizing Availability Groups. Occurs when SQL Server is waiting to access partner list. It does not mean partners are synchronizing data like HADR_SYNC_COMMIT. This wait type is common and small values indicate regular activity. If values are excessive see suggested solutions below.
- Examine Windows Failover Clustering logs for any issues
- Check the SQL Server error log for more information
- Examine wait statistics on the instance for other Availability Group issues. Investigate accordingly
AlwaysOn Availability Groups Troubleshooting and Monitoring Guide