Event notifications are not always going out.
Event notifications are not always being sent. Our group has a repeating event on the first of the month, set for 12am-1am. (It's just a notice of who is that month's secretary.) The e-mails for Feb 1st and March 1st were not sent. January's was sent. The Feb and March events had been modified from the original repeating event to a 1-time event with the name of the secretary in the event title. According to the user interface, an e-mail reminder should be sent 1 day in advance, but nothing was ever sent. The reminder does not show up in "conversations", so I know it's not just that my spam filter ate it, unless Yahoo's own spam filter also ate the message when it was outgoing.
I noticed that a similar topic was marked solved, but this problem seems to be ongoing for at least some types of events.