iCal default alert bug

Default alerts work when I create an event in Calendar. But they do not work when I create an event from Mail. I use the data detectors to create events all the time, since it imports the proper information regarding time and location. But the tradeoff seems to be that these events never have alerts—even at the time of the event. I saw this in Yosemite and still see it in El Cap. Is there a workaround or a fix?