iMessage notifications missing

In iMessage, when one specific contact messages me, I start to get the notification, but then it disappears as if it was read. It isn't marked as read to the sender, but I have no badge or notification. Sometimes, it never alerts my phone and I would have to go into Messages to see if there are any new messages. The sender is sending from a Mac, but many other contacts do to, as well as other devices. The sender also never sees my their messages as read even though I have read receipts on. (This has stayed an issue through iOS 7 and Mavericks). Any ideas?