There’s a thread with about 20 responses over in tech support as well.
I’ve had this issue and haven’t been able to do any dungeons for at least 2 days now.
I get stuck at 70% loading, then get booted to the login screen. When I log back in character with this name already exists error pops up.
Have to wait for the server to register that my character is no longer connected then I’m able to log in only to have this happen again and the cycle repeats.
Sigh.