as far as I can tell, it is only happening in one thread. The recipient is able to reply to all of my imessages (and they can even reply to green bubbles/text messages), but sometimes it shows a dotted bubble and I dont know what the original message I sent says. I have a 16pro and its running the most recent iOS, but it was also happening with the previous iOS.
I synced my imessage and it still
isnt showing the original message.