Broken login process for Steam version

[OddOne]

I created a fresh account with Atlus, and that works fine (including logging into the Atlus website). However, I cannot log into the game proper as the response from the game is "ID/Password does not match." Yes, I typed my credentials in correctly. No, capslock isn't on. Yes, I'm running it as an administrator to make sure that's not it.

Apparently the Steam version of the game has an "issue."