Recaptcha version 3 (invisible mode) not working

I noticed that he makes the request for api from Google. However, the `this.captcha.getResponse()` method is returning empty.

in my html: 
```
<re-captcha class="center-block" site_key="<MY_SITE_KEY>"
                    (captchaResponse)="handleCorrectCaptcha($event)" [size]="'invisible'"></re-captcha>
```
