Ionic not displaying page until window resize

app.component.ts

import { Component } from '@angular/core';
import { Platform } from 'ionic-angular';
import { StatusBar } from '@ionic-native/status-bar';
import { SplashScreen } from '@ionic-native/splash-screen';
import {Observable} from 'rxjs/Rx';
import { Subject } from "rxjs/Rx";

import { HomePage } from '../pages/home/home';
@Component({
  templateUrl: 'app.html'
})
export class MyApp {
  rootPage:any;

  constructor(platform: Platform, statusBar: StatusBar, splashScreen: SplashScreen) {
    
    platform.ready().then(() => {
      
      let source = this.init();
      source.subscribe( 
        result => {
          this.rootPage = HomePage;
        });
    });
  }

  private init() : Observable<any> {
    let db = window["openDatabase"]( "test", "1.0", "bobo_test", 50 * 1024 * 1024);
    
    let observable = new Subject();

    db.transaction( (transaction) => {

      transaction.executeSql("SELECT count(*) FROM sqlite_master", [],
        (tx, result ) => {
          console.log( `db.query compelte: ${JSON.stringify(result)}`);
          observable.next( result );
          observable.complete();

        },
        (tx, error) => {
          console.error( "db.query error: " + JSON.stringify(tx) + "\n" + error.message );
          observable.error( error.message );
          observable.complete();
        }
      );
    });

    return observable;
  }
}