If you find AlwaysOn Health Events grayed out and you are not able to see extended events.
Please find below screenshot. When you connect Dashboard of AlwaysOn, you will find View AlwaysOn Health Events grayed out (Below screenshot is not grayed out, this is to give the instruction where we should look at).
Step 1. Execute SQL
IF EXISTS (SELECT * FROM sys.server_event_sessions WHERE name = ‘AlwaysOn_health’)
ALTER EVENT SESSION AlwaysOn_health ON SERVER WITH (STARTUP_STATE = ON);
Step 2. Execute SQL
IF NOT EXISTS (SELECT * FROM sys.dm_xe_sessions WHERE name = ‘AlwaysOn_health’)
ALTER EVENT SESSION AlwaysOn_health ON SERVER STATE = START;