WPF Xaml Storyboard stops after dynamically changing Accent (Mahapps) - wpf

Question

I have a WPF app which is using Mahapps for styling. The user has the ability to change the apps accent and or theme during run time which is done through the ThemeManager (a class provided by Mahapps). I have a Border which I have styled:
<Border Margin="5">
<Border.Style>
<Style TargetType="Border">
<Setter Property="BorderBrush" Value="{DynamicResource AccentColorBrush3}"/>
<Setter Property="BorderThickness" Value="2 2 2 2"/>
<Setter Property="Background" Value="{DynamicResource AccentColorBrush4}"/>
<Setter Property="CornerRadius" Value="0"/>
<Style.Triggers>
<DataTrigger Binding="{Binding IsPopulated}" Value="True">
<Setter Property="BorderBrush" Value="{DynamicResource AccentColorBrush3}"/>
<Setter Property="BorderThickness" Value="2 2 2 2"/>
<Setter Property="Background" Value="{DynamicResource AccentColorBrush4}"/>
<Setter Property="CornerRadius" Value="0"/>
</DataTrigger>
<DataTrigger Binding="{Binding IsPopulated}" Value="False">
<Setter Property="BorderThickness" Value="3"/>
<Setter Property="CornerRadius" Value="2"/>
<DataTrigger.EnterActions>
<BeginStoryboard Name="BeginStoryboard">
<Storyboard>
<ColorAnimation AutoReverse="True"
RepeatBehavior="Forever"
Storyboard.TargetProperty="BorderBrush.Color"
Duration="00:00:01"
From="Transparent"
To="IndianRed"/>
</Storyboard>
</BeginStoryboard>
</DataTrigger.EnterActions>
<DataTrigger.ExitActions>
<StopStoryboard BeginStoryboardName="BeginStoryboard"/>
</DataTrigger.ExitActions>
</DataTrigger>
</Style.Triggers>
</Style>
</Border.Style>
<Grid/>
</Border>
The styling and datatriggers work as expected. The border has a glowing red border brush which fades in and out - this is to grab the users attention. However, when the accent is changed at run time through a settings menu I have created, this seems to remove the animation and the border brush colour becomes the selected accent colour. The border thickness remains at 3 so I can see the setters for the data trigger stay the same, but the storyboard seems to be removed.
Any ideas as to why this is happening?