Access Session Summary Event email not triggering

Running version 5.2.11.
I’m having difficulty getting an “Access Session Ends” event to send an email.
I’ve tested the email settings, and a test email is correctly sent.
Other events (Technician joins/leaves a session) work ok.
In "Event Alert Configuration | “Email Notifications”, I’ve enabled “Access Session Ends” and in “Actions Configuration” selected “Send an Email” & configured it. There are no filters selected.
But no email is sent.
In the Guide, under “Support Session Ends” it says “A remote support session has ended. The contents of this event is configured via the Session Summary tab”. I’m not quite sure whwre this tab is - maybe I’ve missed something there.
Hope someone can cast some light on this for me.
Cheers, Don