Activity stream mention on a form was not triggering emails to the mentioned userDescriptionThe Activity stream @ mention functionality on a form suppose to trigger an email to the user who is mentioned, but the email was not triggered on an affected instance.Cause"Activity Stream @Mention Email" notification record was not active on the affected instance (You can verify this via "System Notification=>Email=>Notoifications and filter for Name = Activity Stream @Mention Email").Thus users couldn't set the "Activity Stream @Mention Email" notification preference to true.Hence, @ mention emails are not created and sentResolutionPlease activate the "Activity Stream @Mention Email" notification record on the affected instance and then set this user preference true for a user, this should resolve the issue.Also, make sure the email field is set on sys_user record, thus it will create cmn_notif_device record to send an email notification for @mention functionality.