BoundedMapView not working correctly

Is anyone familiar with BoundedMapView here?

I've posted my question in stackoverflow here to no avail.

I've implemented it but it doesn't seem to be working properly. Firstly the center does not seem to be set at all no maptiles will be displayed.

Also when I tried setting the centerpoint to the first location, maps can be seen. However upon a slight scrolling gesture on the screen, everything disappears and grey maptiles appear again.