xaml - Why placeholders from entry and labels is not visible properly in Xamarin Forms?

Question

My problem is that I'm developing an app via an emulator and everything is working good, but on my Android smartphone I have an issue, all placeholders and labels don't appear.

My code:

<ContentPage.Resources>
        <ResourceDictionary>
            <converters1:InverseBoolConverter x:Key="InverseBoolConverter"/>
            <converters1:FirstValidationErrorConverter x:Key="FirstValidationErrorConverter"/>
        </ResourceDictionary>
    </ContentPage.Resources>
    <ContentPage.Content>
        <ScrollView>
        <StackLayout Padding="30"
                         VerticalOptions="CenterAndExpand">

            <Label Text="Logare"
                      Style="{StaticResource TitleStyle}"/>
            <Image Source="ic_login.png" WidthRequest="100" HeightRequest="100"/>
                <!--IDNP-->
            <Entry Text="{Binding IDNP.Value}" 
                       Placeholder="IDNP" HorizontalOptions="FillAndExpand">
                <Entry.Behaviors>
                    <behaviours:EntryLineValidationBehaviour IsValid="{Binding IDNP.IsValid}"/>
                </Entry.Behaviors>
            </Entry>

            <Label Text="{Binding IDNP.Errors, Converter={StaticResource FirstValidationErrorConverter}}"
                        IsVisible="{Binding IDNP.IsValid, Converter={StaticResource InverseBoolConverter}}"
                         Style="{StaticResource ErrorTextStyle}"/>


            <!--Password-->

            <Entry Text="{Binding Password.Value}"
                         Placeholder="Parola" IsPassword="True" HorizontalOptions="FillAndExpand">
                <Entry.Behaviors>
                    <behaviours:EntryLineValidationBehaviour IsValid="{Binding Password.IsValid}"/>
                </Entry.Behaviors>
            </Entry>

                <Label Text="{Binding Password.Errors, Converter={StaticResource FirstValidationErrorConverter}}"
                        IsVisible="{Binding Password.IsValid, Converter={StaticResource InverseBoolConverter}}"
                        Style="{StaticResource ErrorTextStyle}"/>


            <Button Text="LOGARE" x:Name="Button"
                        Command="{Binding LogInCommand}"/>
        </StackLayout>

            </ScrollView>
    </ContentPage.Content>
</ContentPage>

Answer 1

等待大神答复