When I make changes to my calendar on my Mac, I've noticed that the calendar on my iPhone and iPad are not updating until I open the apps. For example, I moved a meeting from today to tomorrow on my Mac and two hours later I get a notification on my iPhone about the meeting for today. It should have automatically moved it to tomorrow. This is something that used to work five even though I usually close all apps running in the background. Shouldn't the calendar app update anyway? Is there a setting I'm missing?