WPF Animation not working on "fast" property change

I am having trouble making an animation work in WPF with DataTriggers when the property binded is changes "fast". The animation is a simple flash of an element. My problem is even after a long time searching on the internet, i can't figure out a way to explain why toggling the property ON and OFF in 2 consecutives lines doesn't work, but if the thread sleeps 1ms it does. I tried inserting other instructions to "waste" some time but it doesn't work either.

Here is the property in question in the viewmodel:

private bool m_activateFlash;
    public bool ActivateFlash
    {
        get { return m_activateFlash; }
        set
        {
            SetPropertyBackingField(ref m_activateFlash, value);
        }
    }

Here is the XAML :

<DataTemplate x:Key="JobTemplate" DataType="viewModel:JobViewModel">
    <Border Margin="8,4,8,4" BorderThickness="1" BorderBrush="{StaticResource BorderBrush}" Background="{StaticResource JobBackgroundBrush}">
        <Border.Resources>
            <Storyboard x:Key="Blink">
                <ColorAnimation  Storyboard.TargetProperty="(Border.Background).(SolidColorBrush.Color)" FillBehavior="Stop" 
                                 Duration="0:0:0.4" To="{StaticResource JobBackgroundFlash}" RepeatBehavior="3x" AutoReverse="True"/>
            </Storyboard>
        </Border.Resources>
        <Border.Style>
            <Style TargetType="Border">
                <Style.Triggers>
                    <DataTrigger Binding="{Binding ActivateFlash, NotifyOnTargetUpdated=True}" Value="True">
                        <DataTrigger.EnterActions>
                            <BeginStoryboard Storyboard="{StaticResource Blink}" Name="BeginBlinkStoryBoard"/>
                        </DataTrigger.EnterActions>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </Border.Style>
        [....]

And finally here is where it is causing me problems in the viewmodel :

    private void TriggerFlash()
    {
        ActivateFlash = true;
        System.Threading.Thread.Sleep(1); // HACK DOESN'T WORK WITHOUT THIS LINE
        ActivateFlash = false;
    }

I looked up EventTriggers as maybe a way to circumvent the issue, but I feel DataTrigger is the logical way to achieve what i want. Any help is really appreciated :) EDIT It appears i wasnt invoking Trigger flash on the main thread. Simply calling Dispatcher.Invoke(...) solved the problem

Thanks

Adam