ResourceNotFoundException: user pool xyz does not exist - Cognito adminConfirmSignup

For some reason, only the adminConfirmSignup gives the user pool does not exist error. The CognitoUser doesn't give that error. Please refer to the code below:

let cognitoUser = new AmazonCognitoIdentity.CognitoUser(userData)
var cognitoAdmin = new AWS.CognitoIdentityServiceProvider({ region: process.env.COGNITO_POOL_REGION! });
await cognitoAdmin.adminConfirmSignUp(confirmParams, async(err, data) => { //Only this gives the user pool does not exist error
    if (err) {
        console.log(`This is the admin user confirm error ---> ${err}`)
    } else {
        console.log(`Entered else`);
        await cognitoUser.authenticateUser(authenticationDetails, {
            onSuccess: async(result) => {
                cognitoUser.changePassword(resetDetails.currentPassword, resetDetails.newPassword, (err, data) => {
                    if (err) {
                        reject(err);
                    } else {
                        console.log(`This is the success response of cognito change password -----> ${JSON.stringify(data)}`);
                        resolve(data);
                    }
                })
            },
            onFailure: (error) => {
                console.log(`This is the onFailure error ----> ${JSON.stringify(error)}`);
                reject(error);
            }
        })
    }
})

The password reset works if I use the CognitoUser methods (when I manually confirm the user and use only the cognitoUser methods to authenticate and reset the password).

from ResourceNotFoundException: user pool xyz does not exist - Cognito adminConfirmSignup