StopStoryboard doesn't stop endless animation - wpf

Question

I'm drawing a Polygon on a Canvas as a battery indicator. If the battery percentage drops below a threshold value, the polygon should start a pulsing animation, if the percentage rises back above the threshold, the pulsing should stop. For that I am using a DataTrigger that binds to a bool in the view model that tells me whether or not to run the pulsing animation loop at the moment.
At first, the animation is off, and as soon as the percentage drops, it starts pulsing as intended. But when the percentage levels rise again, I can't find any way to make the pulsing animation stop.
This is my current XAML code:
<Polygon.Style>
<Style TargetType="Polygon">
<Style.Triggers>
<DataTrigger
Binding="{Binding IsLowPercentage}"
Value="True">
<DataTrigger.EnterActions>
<BeginStoryboard Name="Pulse">
<Storyboard>
<DoubleAnimation
AutoReverse="True"
RepeatBehavior="Forever"
Storyboard.TargetProperty="Opacity"
From="1"
To="0.2" />
</Storyboard>
</BeginStoryboard>
</DataTrigger.EnterActions>
<DataTrigger.ExitActions>
<StopStoryboard BeginStoryboardName="Pulse" />
<!--<RemoveStoryboard BeginStoryboardName="Pulse" />-->
<!--<BeginStoryboard>
<Storyboard>
<DoubleAnimation
Storyboard.TargetProperty="Opacity"
To="1"
Duration="0:0:0.2" />
</Storyboard>
</BeginStoryboard>-->
</DataTrigger.ExitActions>
</DataTrigger>
</Style.Triggers>
</Style>
</Polygon.Style>
I found two questions (1, 2) about this which have the same use-case, and StopStoryboard seems to do the trick for them, but not for me.
Next to StopStoryboard, I also tried RemoveStoryboard and another BeginStoryboard (because according to this answer a storyboard automatically stops if the same dependency propery is animated by a new storyboard). The regarding codes are shown in the commented part. I tested all combinations, that is Stop, Remove, Begin alone, Stop+Remove, Stop+Begin, Remove+Begin or Stop+Remove+Begin in combination, but nothing seems to work, the pulsing effect just continues forever.
I also considered different naming scopes as the issue, but my storyboards are even in closer naming scopes (same DataTrigger) than this example using StopStoryboard from Microsoft themselves, and my code is also very similar to this other example from Microsoft, but my animation is endless.
I have validated that the bool is in fact set to true or false respectively, and I see that all other values bound to the same view model are displaying the updated values from that view model, so that should be fine.
Everybody seems to be fine using StopStoryboard, but something about my code is wrong so it doesn't work for me.