This is not a Query, it is an answer. I've looked everywhere and it seems no one has the answer to this yet so I'm going to give you one.
Turn off WiFi and data before the message hits 'S'. leaving it at the '...' stage.
Then Air-plane mode.
Close the app.
I'd say leave it for a bit then restart your phone.
It should have an error message now which asks you to re-send it. Just delete it. :)
I left mine for like, 20 mins before resetting. Not too sure yet if waiting is necessary yet or not but if it doesn't work instantly for you then this is probably why. :DOther - Electronics2 months ago