UI Stops updating when navigating back to a page only on Android 5.1.1

For some reason when I leave a page and then navigate back to it. When I try to type in an Entry or select from a Picker, the value is not displayed on the UI. The keyboard still appears and I can see the text in the autocomplete but the UI remains blank.

This doesn't happen on Android 6.0

The page in question looks like this

    <Image x:Name="ImageUpload" Source="Upload"/>

    <Label x:Name="labelUpload" Text="" HorizontalOptions="Center"
        VerticalOptions="Center"/>

    <StackLayout Orientation="Vertical" Margin="20, 0, 20, 0">
        <ActivityIndicator x:Name="spinner" IsRunning="True" IsVisible="False"/>
        <ProgressBar x:Name="uploadProgress" IsVisible="False" Margin="30, 0, 30, 0" Progress="{Binding uploadProgress}"/>
        <Label HorizontalOptions="Center" x:Name="status"/>
    </StackLayout>

    <StackLayout Margin="20, 0,0,0" Orientation="Horizontal">
        <Label VerticalOptions="Center"  Text="Fail Reason"/>
        <Picker HorizontalOptions="FillAndExpand"  ItemsSource="{Binding Reasons}" x:Name="FailReason"></Picker>
    </StackLayout>
    <StackLayout Margin="20, 0,0,0" Orientation="Horizontal">
        <Label VerticalOptions="Center"  Text="Additional Comments"/>
        <Entry HorizontalOptions="FillAndExpand" x:Name="Comment" />
    </StackLayout>
    <Entry HorizontalOptions="FillAndExpand" x:Name="Comment" />


    <StackLayout Orientation="Horizontal" HorizontalOptions="Center">
        <Label VerticalOptions="Center" Text="Attach additional files"/>
        <Button Clicked="OpenFileExplorer" Text="Add"></Button>
    </StackLayout>

    <ListView x:Name="files" ItemsSource="{Binding files}">
        <ListView.ItemTemplate>
            <DataTemplate>
                <ViewCell>
                    <ViewCell.ContextActions>
                        <MenuItem Clicked="RemoveImage" CommandParameter="{Binding .}" Text="Delete"/>
                    </ViewCell.ContextActions>
                    <StackLayout Orientation="Horizontal">
                        <Image  Source="{Binding thumbnail}"></Image>
                        <Label Text="{Binding fileName}" FontSize="18"/>
                    </StackLayout>
                </ViewCell>
            </DataTemplate>
        </ListView.ItemTemplate>
    </ListView>
</StackLayout>