Keep ListView.HeaderTemplate visible/static/sticky in UWP

Apply this style to your ListView and you will have static header

    <Style TargetType="ListView" x:Key="FixedHeaderListViewStyle">
        <Setter Property="IsTabStop" Value="False" />
        <Setter Property="TabNavigation" Value="Once" />
        <Setter Property="IsSwipeEnabled" Value="True" />
        <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled" />
        <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto" />
        <Setter Property="ScrollViewer.HorizontalScrollMode" Value="Disabled" />
        <Setter Property="ScrollViewer.IsHorizontalRailEnabled" Value="False" />
        <Setter Property="ScrollViewer.VerticalScrollMode" Value="Enabled" />
        <Setter Property="ScrollViewer.IsVerticalRailEnabled" Value="True" />
        <Setter Property="ScrollViewer.ZoomMode" Value="Disabled" />
        <Setter Property="ScrollViewer.IsDeferredScrollingEnabled" Value="False" />
        <Setter Property="ScrollViewer.BringIntoViewOnFocusChange" Value="True" />
        <Setter Property="UseSystemFocusVisuals" Value="True" />
        <Setter Property="ItemContainerTransitions">
            <Setter.Value>
                <TransitionCollection>
                    <AddDeleteThemeTransition />
                    <ContentThemeTransition />
                    <ReorderThemeTransition />
                    <EntranceThemeTransition IsStaggeringEnabled="False" />
                </TransitionCollection>
            </Setter.Value>
        </Setter>
        <Setter Property="ItemsPanel">
            <Setter.Value>
                <ItemsPanelTemplate>
                    <ItemsStackPanel Orientation="Vertical" />
                </ItemsPanelTemplate>
            </Setter.Value>
        </Setter>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="ListView">
                    <Border BorderBrush="{TemplateBinding BorderBrush}" 
                            Background="{TemplateBinding Background}" 
                            BorderThickness="{TemplateBinding BorderThickness}">
                        <Grid>
                            <Grid.RowDefinitions>
                                <RowDefinition Height="Auto"/>
                                <RowDefinition/>
                            </Grid.RowDefinitions>

                            <ContentControl Content="{TemplateBinding Header}"
                                                ContentTemplate="{TemplateBinding HeaderTemplate}"
                                                ContentTransitions="{TemplateBinding HeaderTransitions}"/>

                            <ScrollViewer x:Name="ScrollViewer"
                                          Grid.Row="1"
                                        TabNavigation="{TemplateBinding TabNavigation}"
                                        HorizontalScrollMode="{TemplateBinding ScrollViewer.HorizontalScrollMode}"
                                        HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"
                                        IsHorizontalScrollChainingEnabled="{TemplateBinding ScrollViewer.IsHorizontalScrollChainingEnabled}"
                                        VerticalScrollMode="{TemplateBinding ScrollViewer.VerticalScrollMode}"
                                        VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}"
                                        IsVerticalScrollChainingEnabled="{TemplateBinding ScrollViewer.IsVerticalScrollChainingEnabled}"
                                        IsHorizontalRailEnabled="{TemplateBinding ScrollViewer.IsHorizontalRailEnabled}"
                                        IsVerticalRailEnabled="{TemplateBinding ScrollViewer.IsVerticalRailEnabled}"
                                        ZoomMode="{TemplateBinding ScrollViewer.ZoomMode}"
                                        IsDeferredScrollingEnabled="{TemplateBinding ScrollViewer.IsDeferredScrollingEnabled}"
                                        BringIntoViewOnFocusChange="{TemplateBinding ScrollViewer.BringIntoViewOnFocusChange}"
                                        AutomationProperties.AccessibilityView="Raw">
                                <ItemsPresenter 
                                                Footer="{TemplateBinding Footer}"
                                                FooterTemplate="{TemplateBinding FooterTemplate}"
                                                FooterTransitions="{TemplateBinding FooterTransitions}"
                                                Padding="{TemplateBinding Padding}" />
                            </ScrollViewer>

                        </Grid>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>