AWS Cognito

Hi, I am trying to setup a simply Ionic project with the ability to sign in with AWS cognito services. I have tried AWS.SDK, but was not able to sign in, just came back with blank err object. I have also tried AWS Amplify, but also not able to sign in (though I am able sign up, change password and confirm ok, but not able to login ).
I have even tried the IONIC AWS template but fails with errors around not able to find buffer. Any guidance would be great.