The answer depends on how you create your development time data. Seems like you used ViewModel? If so, check at what point you create it. for example, do you create it as an element in your XAML or create it in the view constructor?
Indeed, there should be no difference in what you see during development in Visual Studio compared to what you see during development in Expression Blend. If so, you may need to perform a clean one and rebuild the project in one of the programs. If the problem still persists, try closing Blend and reopening it.
Jared Bienz - MSFT
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