I am creating an EventTrigger in codebehind in OnInitialized method. I get an InvalidCastExceptionwhenever I try to add something to the Actions collection. Same thing happens in Visual Studio debugger when I try to watch the Actions collection (same for Enter/ExitActions)

The exception:
System.InvalidCastException: 'Unable to cast object of type 'Noesis.BaseUICollection' to type 'Noesis.TriggerActionCollection'.'

Code sample where the exception happens:

private void SetupIntroStoryboard()
{
var newBoard = CreateNewStoryboard();
if (newBoard == null)
{
return;
}
Triggers.Clear();
var newTrigger = new EventTrigger();
newTrigger.RoutedEvent = FrameworkElement.LoadedEvent;
newTrigger.Actions.Add(new BeginStoryboard() { Storyboard = newBoard });
Triggers.Add(newTrigger);
}