Same problem here.
After I change my character ID, I can not use that character’s guild to upload the log. I used https://www.warcraftlogs.com to login my WCL account and tryied to update my character information, but update was no code. Then I tryied to relink my battle tag, but can not linked to Battle.net TW. It seems like tw.battle.net is not being used by battle.net itself but redirected to kr.battle.net, so we can not login by use tw battle net account or any action that have to linked to Battle.net.
I read the theard Can't Link to Battle.net account here, it seems like had the
similar problem at Apr. Any reaction can fix it ? Thank you.