title: Getting UserNotFoundException on a specific user in Cognito
body: <p>I'm using cognitoUser.authenticateUser to authenticate users. This works for all 30 users I have in Cognito except one. (AWS.CognitoIdentityServiceProvider.CognitoUser)</p>
  <p>Specifically I can authenticate the user by username but not verified email address. This is the only user I cannot authenticate by email address. The call returns UserNotFoundException when passing email address.</p>
  <p>The user's settings are exactly the same as the other users and the verified email address is very simple.</p>
  <p><a href="https://i.stack.imgur.com/EN78D.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EN78D.png" alt="enter image description here" /></a></p>
  <p>email: foo@bar.com</p>