I have found almost all "disappearing appointment" issues involve delegates. You should never have more than one delegate on your account and only if you intend for that person to completely manage your calendar on your behalf. You see if a delegate deletes a meeting invite of yours from their inbox it will pull it off YOUR calendar. You can see how the more delegates you have this would exponentially increase the problems this causes. If you need to assign permissions to view your calendar, right-click the calendar folder on your folder list and assign permissions. Remove all delegates with the exception of one who completely manages your calendar on your behalf. This is a <b>feature</b>, not a <b>problem</b>...

I have found almost all "disappearing appointment" issues involve delegates. You should never have more than one delegate on your account and only if you intend for that person to completely manage your calendar on your behalf. You see if a delegate deletes a meeting invite of yours from their inbox it will pull it off YOUR calendar. You can see how the more delegates you have this would exponentially increase the problems this causes. If you need to assign permissions to view your calendar, right-click the calendar folder on your folder list and assign permissions. Remove all delegates with the exception of one who completely manages your calendar on your behalf. This is a <b>feature</b>, not a <b>problem</b>...