I have been playing Diablo Immortal since release and my Battle.net User ID has always been Adaitanley#XXXX which is my main characters name. I recently created an alternate character on a different server named Draston and my Battle.net User ID changed itself to that characters name (Draston#11353). I am wanting to keep my original User ID of Adaitanley#XXXX and will be attempting to create another new character named that on another server to see if it fixes the issue.
This happened to me as well. I’d like to change it back but don’t know how. Let me know if you figured it out please. 