Ti.Map max Zoom level on iOS

I have created a ti.map view with an annotation, so far everything is working fine.

On android it works completely as expected, but on iOS the map behaves strange at proper zoom level.

I have an UI element, on click I wanna zoom to the place defined in code below.

This works only at the first time after I have launched the app. When I call the same function the second time the map will zoom out.

$.mapview.setLocation({
            "longitudeDelta": 0.001847,
            "latitudeDelta": 0.001187,
            "longitude": 6.773784,
            "latitude": 51.226154,
            "animate": true
        });

Can someone please tell me why I can reach the zoom level only once per launch, is there any known bug ?