WPF TabStop TextBoxes not working on Win10

I am struggling with testing of my wpf application, in which I have a window with TextBoxes, that contain a custom style from Application.Resources

The style implements a placeholder, and because it interfered with tabbing(it focused the placeholder instead of TB content) I had to add some IsTabStop code.

It's working perfectly fine when Im debugging and also the release exe on Win7, but the tabbing doesn't work on Win10, it simply ignores TextBoxes and just tabs trough other controls that don't have this style implemented.

Any help would be great!

Here is the style code:

<Style x:Key="placeHolderNoline" TargetType="{x:Type TextBox}" BasedOn="{StaticResource tb}">
            <Setter Property="IsTabStop" Value="False"/>

            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type TextBox}">


                        <Grid>
                            <TextBox Text="{Binding Path=Text,
                                            RelativeSource={RelativeSource TemplatedParent}, 
                                            Mode=TwoWay,
                                            UpdateSourceTrigger=PropertyChanged}"
                             x:Name="textSource" 
                             Background="Transparent" 
                             Panel.ZIndex="2" 
                                 BorderThickness="0,0,0,0"/>


                            <TextBox Text="{TemplateBinding Tag}" Background="{TemplateBinding Background}" Panel.ZIndex="1" BorderThickness="0" IsTabStop="False">

                                <TextBox.Style>
                                    <Style TargetType="{x:Type TextBox}">
                                        <Setter Property="Foreground" Value="Transparent"/>
                                        <Style.Triggers>
                                            <DataTrigger Binding="{Binding Path=Text, Source={x:Reference textSource}}" Value="">
                                                <Setter Property="Foreground" Value="LightGray"/>
                                            </DataTrigger>
                                        </Style.Triggers>
                                    </Style>
                                </TextBox.Style>
                            </TextBox>
                        </Grid>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>

Edit: tb style:

 <Style TargetType="TextBox" x:Key="tb">

            <Setter Property="Foreground" Value="WhiteSmoke"/>
            <Setter Property="Background" Value="#33FFFFFF"/>
            <Setter Property="BorderThickness" Value="0"/>
        </Style>

Solution

A ControlTemplate of a TextBox is not supposed to include another or two other TextBox elements.

Try this style:

<Style x:Key="placeHolderNoline" TargetType="TextBox" BasedOn="{StaticResource tb}">
    <Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"/>
    <Setter Property="BorderBrush" Value="#FFABAdB3"/>
    <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type TextBox}">
                <Border x:Name="border" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="True">
                    <Grid>
                        <TextBlock Text="{TemplateBinding Tag}" Foreground="LightGray" Background="{TemplateBinding Background}">
                            <TextBlock.Style>
                                <Style TargetType="{x:Type TextBlock}">
                                    <Setter Property="Visibility" Value="Collapsed"/>
                                    <Style.Triggers>
                                        <DataTrigger Binding="{Binding Path=Text, RelativeSource={RelativeSource AncestorType=TextBox}}" Value="">
                                            <Setter Property="Visibility" Value="Visible"/>
                                        </DataTrigger>
                                    </Style.Triggers>
                                </Style>
                            </TextBlock.Style>
                        </TextBlock>
                        <ScrollViewer x:Name="PART_ContentHost" Focusable="false" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden"/>
                    </Grid>
                </Border>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsEnabled" Value="false">
                        <Setter Property="Opacity" TargetName="border" Value="0.56"/>
                    </Trigger>
                    <Trigger Property="IsMouseOver" Value="true">
                        <Setter Property="BorderBrush" TargetName="border" Value="#FF7EB4EA"/>
                    </Trigger>
                    <Trigger Property="IsKeyboardFocused" Value="true">
                        <Setter Property="BorderBrush" TargetName="border" Value="#FF569DE5"/>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>