So I'm running el Capitan (10.11.6) and whenever I go to edit an existing event and add a new alert to it asks if I want to do it to that one or all of them. I choose all of them (it's reoccurring every week) and I close the dialogue box. After checking the event the alert is gone. This doesn't happen if I add alerts to a new event, only to existing events and when I choose to change all future events. Any solutions?
MacBook
Pro, OS X El Capitan (10.11.4)