javascript async/await not waiting in AWS Lambda?

Question

I'm learning AWS lambda and I'm also new to JavaScript. Always a great idea to have multiple variables in play at the same time. But, I've written 2 version of the code below. The first works. The second does not and I cannot figure out why.

The only difference between the 2 programs is that I've created the addUser function to execute the Cognito call.

Working code:

const moment = require('moment');
const AWS = require('aws-sdk');
const waitup = require('await-to-js');

exports.handler = async(event)=>{
   let body=JSON.parse(event.body);
   let email=body.email;
   let fullName=body.name;
   let password=body.password;
   let phoneNumber=body.phoneNumber;

   const cognitoParams = {
      UserPoolId: "ab-west-6_FRz8PQp3t",
      Username: email,
      TemporaryPassword: Math.random().toString(36).substr(2, 10),
      UserAttributes: [{
         Name: "email",
         Value: email,
      },
      {
         Name: "email_verified",
         Value: "true",
      },
      ]
   };

   let actResponse;
   var cognito = new AWS.CognitoIdentityServiceProvider();   
   try {
      actResponse=await cognito.adminCreateUser(cognitoParams).promise();
      console.log("actResponse", actResponse);
   } catch(err) {
      console.log("err", err, err.stack);
      actResponse = err;
   }

   return {
      statusCode: 200,
      body: JSON.stringify(actResponse)
   };
}

Non-working code:

const moment = require('moment');
const AWS = require('aws-sdk');
const waitup = require('await-to-js');

async function addUser(email, fullName, phoneNumber){
   var cognito = new AWS.CognitoIdentityServiceProvider();
   const cognitoParams = {
      TemporaryPassword: Math.random().toString(36).substr(2, 10),
      UserPoolId: "ab-west-6_XXx4VVq",
      Username: email,
      UserAttributes: [{
         Name: "email",
         Value: email,
      },
      {
         Name: "email_verified",
         Value: "true",
      },
      ]
   };

   try {
      let response = await cognito.adminCreateUser(cognitoParams).promise();
      return response;
   } catch(err) {
      return err;
   }
}

exports.handler = async(event)=>{
   let body=JSON.parse(event.body);
   console.log("body", body);
   let email=body.email;
   let fullName=body.name;
   let phoneNumber=body.phoneNumber;
   const accountResponse=addUser(email, fullName, phoneNumber);
   return {
      statusCode: 200,
      body: JSON.stringify(accountResponse)
   };
}