How to trigger Authenticator App as 2FA option

Hi all,

I manage multiple Amazon accounts. When accepting an invite to a new client account, it used to give me the option to enter my 2FA—either right away, or on the second try. Now, that’s not happening at all on every new invite I receive. My phone number is already used, so it’s not an option.

Does anyone know how to trigger Authenticator App as an option consistently? I’ve asked clients to set it as the preferred 2FA before inviting me and it hasn’t worked.

Also, if you know of any other ways to get reliable and affordable 2FAs via phone, I’d love to know.

Thank you!