I'm still having weird messaging issues when I delete multiple messages and close the messages app by "force quitting" per say and then I open it up again and all the messages are gone. Restarting helps but also brings back all the messages I've deleted months ago it's a little annoying just wondering if their is a fix for this or not. I'm currently running iOS 8.4 on my iPhone 6 and this also happened while running iOS 8.3.