My Imessage has been having issues lately. The biggest problem is that occasionally I get sent a message, but nothing happens. My phone doesn't go off and no message appears in the thread; to my knowledge I did not receive a message in any way. My last message to them says 'delivered' when they have read receipts turned on. When I check back a few hours later a new message is usually sitting there with a time stamp from hours earlier, yet I had no idea that I got one at all. This usually happens once or twice a day, and it needs to end. Any ideas on how to fix it?