AWS Cognito initiateAuth response empty when trying to authenticate a user in JavaScript

I’m trying to authenticate a user with AWS Cognito using the USER_PASSWORD_AUTH flow in JavaScript. However, the response from initiateAuth is always empty. Here’s the code I’m using:

        var cognitoidentityserviceprovider = new AWS.CognitoIdentityServiceProvider({region: 'eu-central-1'});

        const poolData = {
            UserPoolId: "userPoolId",
            ClientId: "clientId",
        }

        let username = document.getElementById('username').value;
        let password = document.getElementById('password').value;
            var aws_params = {
            AuthFlow: "USER_PASSWORD_AUTH", 
            AuthParameters: {
                "PASSWORD": password, 
                "SECRET_HASH": "secretHash", 
                "USERNAME": username
            }, 
            ClientId: "clientId", 
        };

        response = cognitoidentityserviceprovider.initiateAuth(aws_params);

However, the response object is consistently empty, like this:

{
"request": {…},
"data": null,
"error": null,
"retryCount": 0,
"redirectCount": 0,
"httpResponse": {…},
"maxRetries": 3,
"maxRedirects": 10

}

I did the same thing but using a django view and it works: i got the token from cognito. But in js I’m stuck.

Any guidance is appreciated!