As far as I know your calendar should continue to remind you even when it is closed.
A lot of things are wonky with mine, very randomly, it's very irritating because I can never really rely on it then.
Strangest thing happened with my calendar this morning I noticed. But it's been more than a few days that it's been misbehaving. My phone did not alert me to an appointment I had yesterday and I knew it was this week sometime so I went to look for it on my computer and it was not there. Trouble is, I couldn't find it on my phone either but I am SURE I put it in there. I also had another one that was upcoming that I was sure I had put in there on my macbook just the other day. So I redid that one, and it didn't show up on my phone and most of my month looked blank when viewed on the 'month' view. Until I went to view the 'day' view and then clicked "today" down in the lower right hand corner to see all the upcoming events. THEN they all were there in that view, but many recently added appointments hadn't been indicated as being on the calendar in any other view nor on my macbook. Now that I had viewed them as a list of upcoming events in the 'today' view on my phone, suddenly they all appeared on my calendar on macbook and iPhone. I did not change a thing except to look at a different view.
This is very strange to me. Viewing a calendar differently should not change the calendar or suddenly cause it to sync. In addition my daughter's calendar kept not syncing but suddenly now started working again when neither of us have changed anything
Oh and yes, I did miss my appointment yesterday because of this.
