Sign in with Apple ASAuthorizationAppleIDCredential returns `nil` in email field

When user do first time login with 'Sign in with Apple', ASAuthorizationAppleIDCredential returns correct email address in `email' field.
But after signing out and doing login again with the same Apple ID, ASAuthorizationAppleIDCredential gives nil in `email` field.
What if first time `Sign in with Apple` was successfull but due to some reason sign up with our own server gets failed? Second time we'll not be able to get the user email.