Board Thread:Love Live! School Idol Festival Lounge/@comment-11148831-20160518151457/@comment-11148831-20180803162243

Basically, they only send authentication codes to accounts that seem to still log in despite being in the middle of account recovery process (e.g. you're emailing them for account recovery, but the account is still active). This is for when they need to further confirm if you are the owner of the account. Like for example, cases like you can't get past the title screen because the app crashes or something. Say, they have enough details, but aren't sure if you are the owner of that account still, they will send an authentication code to where that account is currently logged in and you, in return, will email them with the authentication code that you saw in-app to confirm you are the owner of that account.

If this is not similar to your case, then you will not receive an authentication code. Once they confirm your account details, you will receive transfer credentials immediately.