Hey @andrew.pla - welcome to the Auth0 Community!
Are you sure you haven’t been previously using a username/password account, and just now switched to a Social login? Accounts would be different, so if you initially logged in using username/password, you have to log in with it again - the same way with any of our social logins, if you were using Google, for example, you have to use Google again.
Let me know if this helps.
Thanks!