Providers ionic , wont work when apk is generated

I have a button when pressing it performs the request for some data. So, in my ts file of the page where the button is, I call the function in my provider.

The main problem comes when I compile my application for android platform (Generate apk with ionic cordova build --release android, then I Sign the apk, align and install it). In that case, when I press the button nothing happens, I debugged the code (I added some alerts), but only the first line of the function (The alert that I added) is executed, never returns anything.

But… If I run the app with the commands: ionic cordova run android -l and ionic serve -l. It works like a charm (The provider return the data requested)

I mean, the problem is only when I generate the APK to install it into my device

I also tried with HttpClient but the problem persists.

The code of my Provider is:

Search(path): Promise<any> {

  // -------------  The alert is shown

  return this.http.get(path)
    .map(res => res.json())
    .toPromise()
    .then(
        response => { 

           // -------------  The alert is not shown

            if (typeof response.user.name !== "undefined") {
                this.storage.set('users', JSON.stringify(response));
                return response;
            } else {
                return null;
            }
        },
        error => { 

           // -------------  The alert is not shown

           return null;
        });
} 

I also tried with something like this:

Search(path): Promise<any> {
  // -------------  The alert is shown
  return null;
}

But, also in this case the return line is never executed, only the alert is shown.

The code when I call my provider function in the page where the button is:

this.APIService.Search(final_path).then(res => {
   if (res) {
      this.storage.get('users').then(responseJson => {
         if (responseJson) {
            this.navCtrl.push(ObtenerPage);
         }
      });
    } else {
       this.presentToast("Bad request");
    }
});