title: Some custom markers do not appear on Android react-native-maps
body: <p>In our app, we are obtaining the user location when he logs in (click login -> get location -> save location in redux -> navigate to home screen). When the Home component mounts, it should use the location to get data from the area around the user.</p>
  
  <p>In iOS, all markers render correctly but in Android devices, not all markers are rendered, only some of them (and oddly enough all of them are image1 or image2).</p>
  
  <p>It is only when we call the <em>getDataFromRegion</em> function again that all markers render correctly. Any idea of what we are doing wrong?</p>
  
  <pre><code>class Login extends Component {
  
     handleLogin = (u, p) =&gt; {
  
        getLocation(location =&gt; {
  
           let region = {
              latitude: location.coords.latitude,
              longitude: location.coords.longitude,
              latitudeDelta: 0.06,
              longitudeDelta: 0.06
           }
  
           /* save location in redux */
           this.props.setLocation(region)
           login(u, p).then(() =&gt; _gotoHome())
        })
     }
  }
  
  class Home extends Component {
  
      componentWillMount() {
  
         if(this.props.location !== undefined) {
  
             initialRegion = {
                 latitude: this.props.location.latitude,
                 longitude: this.props.location.longitude,
                 latitudeDelta: 0.06,
                 longitudeDelta: 0.06
              }
          }
       }
  
       componentDidMount() {
          /* set data in redux */   
             this.getDataFromRegion(initialRegion)
       }
  
       render() {
          this.props.data.map((data, index) =&gt; data.visible ? &lt;CustomMarker key={index} data={data}/&gt; : null)
          }
       }
  
  
  class CustomMarker extends Component {
       render() {
           const {data} = this.props
           const coords = { latitude: data.lat, longitude: data.lng }
  
           return (
  
               &lt;MapView.Marker
                   coordinate={coords}
                   onLoad={() =&gt; this.forceUpdate()}
                   tracksViewChanges={Platform.OS === 'android' ? false : true}
               &gt;
                   &lt;Image 
                      onLoad={() =&gt; this.forceUpdate()} 
                      source={data.a === '0' ? image1 : image2}
                      style={{width: 60, height: 60}}
                   /&gt;
               &lt;/MapView.Marker&gt;
           )
       }
  }
  </code></pre>