'esriUI:MapView' is not showing the map in some Android devices.(for example Android 7.0)
Instead of Map it is coming a blank space.
But Map is coming in another android device having save version.
...Also does all the layers switch to a succesful loaded state? If not, check their LoadError property to get an idea what's going on.
Also check the LayerViewStates on the layers (listen for MapView.LayerViewStateChanged) and check the layer states.