Splash Screen not showing up in Android 4.4 version in landscape mode only?

Here is my code:-
styles.xml:

SplashActivity.cs:
[Activity(Theme = "@style/Theme.Splash",
MainLauncher = true,
NoHistory = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation, ScreenOrientation = ScreenOrientation.Landscape)]
public class SplashActivity : Activity
{
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
System.Threading.Thread.Sleep(1500);
StartActivity(typeof(MainActivity));
}
}

Note:- When I remove "ScreenOrientation = ScreenOrientation.Landscape" splash screen shows up. Otherwise it just blinks and then goes off to show black area.