Having a similar problem. My Alert Condition is true, and is set to send daily. It often works as intended, but for some reason it won't send on random days when the condition is True, and the server has checked. Not sure how to move forward.
I am having the same problem. I did not get email notification when my scheduled extract fail. I checked a few settings and it is all set.
Settings-->General-->Refresh Failure Notifications, select Send email to data source and workbook owners when scheduled refreshes fail.
Email notification setting at user level, it is checked for "Send email when scheduled refreshes fail"
How can I check if email is sent out?