Weird message bug

So far I've talked to multiple people about this and searched online for solutions but it's gotten me nowhere. Here's the issue. A while back I started getting a recurring notification from a contact on my phone (my dad). It says he's sent me two picture messages. The problem is, when I tap on the notification it brings me to a blank "send new message" screen. Also, when I open up the conversation thread between us, there's no indication that he's sent me any pictures. It wouldn't be a big deal but it always comes back immediately either when I close the messaging app or after a few minutes, so I can never tell if I have a real notification or not. Has anybody else come across this problem?