In Message + app, after sending a picture through text & it being seen & reviewed by the recipient, later (sometimes days or weeks later) I will get the exclamation triangle informing me it was not delivered when I know it has been. This has happened on both my Galaxy 8+ as well as my Note 9. What is the solution? The examination notification.
Indicating pic was not delivered, but the recipient responded that it was.
Making sure your messages are properly delivered and you are getting the right information about them is a big deal. We don't want confusion over that. How often has this happened? If you click on the notification next to the actual message, what message do you get?