I’ve also been having this problem with email reminders I send to myself, but hadn’t realised that it might be specifically because the send/receive addresses are the same. But this seems to explain why these ones in particular never seem to show up. (I’ve been suffering from this bug with emails that have been in an inbox for more than a week or so, but this explains why my reminders seem to disappear almost instantly).
(Originally posted by thosgood on GitHub.)