FlipView: first item always briefly visible

An alternative temporary and not very intrusive fix consists in :

1.- Declaring your <FlipView x:Name="flipView" Opacity=0.0 ...>

2.- Having the following code-behind:

        bool isLoaded = false;
        private void flipView_SelectionChanged_1(object sender, SelectionChangedEventArgs e)
        {
            if (this.isLoaded && flipView.Opacity != 1.0)
                Dispatcher.RunIdleAsync((a) => { flipView.Opacity = 1.0; }).AsTask();
        }
        int INDEX_ITEM_DISPLAYED_INITIALLY = 1; // '1' should be the index mandated by _your_ business case
        private void flipView_Loaded_1(object sender, RoutedEventArgs e)
        {
            this.isLoaded = true;
            flipView.SelectedIndex = this.INDEX_ITEM_DISPLAYED_INITIALLY;
        }
        private void flipView_Unloaded_1(object sender, RoutedEventArgs e)
        {
            this.isLoaded = false;
        }