i have recently received a few messages, but reponses, although they show up as typed, disappear as soon as you leave the page, just Gone.

I've had a couple of messages come in to me, but my response to them doesn't go through, and is gone from Messenger when I go back in to it. I imagine it's possible that random responses are getting through, but it's likely atypical.

I have not had any success sending a message. A few have managed to come through but not for a long time. It's just not working right.

Try sending a message, instead of responding to one.

I had no idea that was a thing.......where on here would it be found?