I've used Google Messenger for SMS since I got my Note 4 in 2014. About a month ago it began a strange behavior. I will go to compose a text, input & select the persons name, type message and send. As soon as I hit send, the contact I selected visually changes to someone else in my contact list. It turns out the message has only been sent to the contact that Messenger randomly chose and not the original person I intended. This doesn't happen for every text, but does occur about 30% of the time anytime I start a new conversation thread. There seems to be no rhyme or reason for who it switches to and can happen with any contact I initiate the message to. Even sometimes selecting people I've never texted before. The issue seems to be within Messenger itself as I've switched back to the stock Samsung Messages for a few days and haven't had the issue once. Today I started trying Messenger again and what do you know, its happening again. I've cleared data, uninstalled/reinstalled but the only thing that seems to help is clearing all message threads and starting from scratch. If I leave those conversations there I can continue to text and there is no mixup. So I suppose thats my solution for now because I'm not a fan of the stock Samsung app.