This is entirely new and was never an issue before.
I also understand this isn’t as big an issue for a lot of people as it is for people that primarily do RP, but I’ve noticed that once 8.3 dropped, something changed about how the mouse interacts with the UI.
Very minor but if you have the chat bar open (like you’re typing or it’s just empty and open) and you click anywhere on screen that isn’t the chat bar, it closes it. This can get pretty frustrated if you have a longer emote, and it’s just gone without even the alt+up-arrow being able to do anything about it.
This probably seems minor but it’s a pretty big QOL that suddenly changed.
Friend of mine was complaining about this too, seems like a new thing for the patch. Best I can suggest is that when you accidently click somewhere and you lose the chatbox, try pressing enter right after, it had my text in there still.
Hopefully that helps you not lose anymore emotes but it really should be a toggled option.
Especially considering that most RP addons have incorporated some sort of mouseover functionality. Basic roleplay addons like TRP and MRP all the way to stuff like Listener which let you hover over someone to see what they’ve said.
So, while it sucks that this is a thing, gosh dang, I am so relieved to see that it’s not just me and a matter of, “Keep uninstalling and reinstalling components of the game and hope the whole thing doesn’t need it.”