Apple just sent this email to developers:
Two-factor authentication is an additional layer of security designed to ensure that you’re the only person who can access your account, even if someone knows your password. This significantly improves the security of your Apple ID and helps protect the photos, documents, and other data you store with Apple. For more information read Two-Factor Authentication for Apple ID.
If you didn’t enable two-factor authentication and believe someone else has access to your account, you can return to your previous security settings . This link and your Apple ID security questions will expire on February 27, 2019.
If you are like me and have a main personal account for all your Apple ID-related stuff and a separate one for your work email or developer account, you are probably trying to figure out what to do if said account isn’t permanently registered on any of the devices you use.
Here’s the simple workaround:
- Set up a new user account on your Mac
- Login into your iCloud account tied to the developer account under the new macOS user.
- Activate two-factor authentication and add your preferred phone number s a backup.
- Verify you can login into your account via another device or via browser at appleid.apple.com.
- Log out of iCloud account on the temp macOS user and switch back to your primary macOS user.
- Delete the temp account; now, you should be able to use the 2fa via the phone validation every time.
Hopefully, Apple will soon allow dual Work/Personal accounts within a single device or iOS 13 and/or macOS 10.15. Until then, this workaround should help.