Attached Property Behavior with Controls Created in Code

I am conducting an exercise where I am defining a user control using C# code rather than XAML.  I am seeing one strange behavior.  I have an attached property defined thusly:

public static readonly DependencyProperty ElementIDProperty = DependencyProperty.RegisterAttached("ElementID", typeof(uint), typeof(ChartControlBase), new PropertyMetadata(uint.MaxValue));

In another class, I use the AddOwner function to assert a different default value.

public static readonly DependencyProperty ElementIDProperty = ChartControlBase.ElementIDProperty.AddOwner(typeof(PrimaryMarkTopicElement), new PropertyMetadata(0U, new PropertyChangedCallback(PrimaryElement_ElementIDChanged), new CoerceValueCallback(PrimaryElement_CoerceElementID)));

As long as I am dealing with XAML-based controls, this works just as expected.  However, for some reason, with code-based controls, it doesn't...but....ONLY if I am not running under the VS2012 debugger.

The result of this behavior is that the value ends up being uint.MaxValue rather than 0.

What could be causing this odd behavior?

Thanks,

Kelly Hilliard