API call response header in Ionic returns Null in Android Emulator

I am developing an application with Ionic and Angular, I make a post request that returns me a token of the Authorization header, until then I was able to get this value normally with the following code:

data.headers.get('Authorization')

The problem is that it only works when I run the application in the browser; when i try to run on android emulator, it returns null.

It is important to say that the request ends successfully, but the data does not return.

Full code:

 logIn(username, password) {
        this.body = {
          'username': username,
          'password': password 
        };
        this.apiProvider.getToken(this.body, this.headers).subscribe(
          data=>{
             this.storage.set('token', data.headers.get('Authorization'));
             this.navCtrl.setRoot(SideMenuPage);
          }, error=>{
             console.log(error);
             this.msgError = true;
          }
        );
      }

My config.xml:

    <access origin="*" />
    <allow-navigation href="http://api.pet.com.br/*" />
    <allow-navigation href="https://api.pet.com.br/*" />
    <allow-navigation href="data:*" />
    <allow-intent href="http://api.pet.com.br/*" />
    <allow-intent href="https://api.pet.com.br/*" />
    <allow-intent href="http://*/*" />
    <allow-intent href="https://*/*" />
    <allow-intent href="http://*" />
    <allow-intent href="https://*" />
    <allow-intent href="tel:*" />
    <allow-intent href="sms:*" />
    <allow-intent href="mailto:*" />
    <allow-intent href="geo:*" />

Proxy configuration:

"proxies": [
    {
      "path": "*/api",
      "proxyUrl": "http://api.pet.com.br"
    }
  ]

API Call:

export class ApiProvider {
  
  private urlApi:string = "api";

  constructor(
    public http: HttpClient,
    public plt: Platform) {
      if(this.plt.is('mobileweb')) {
        this.urlApi = "api";
      } else {
        this.urlApi = "http://api.pet.com.br";
        /*  If it's not run in the browser it calls the url without the 
        proxy configuration, when I call it from the proxy path in the 
        emulator it gets an HttpErrorResponse: http faiulure during 
        parsing for http://localhost/api/login.
        I do not understand why it replaces with localhost where should 
        be the api url I think. */
      } 
    }

  getToken(body, headers) {
    return this.http.post(this.urlApi + "/login", body, { headers: headers, observe: 'response'});
  }
}