Design time data not visible for Win8.0 apps on Win 8.1

I ended up fixing this and enabling the design-time data again by modifying the ItemsPanelTemplate of the GridView to be a VariableSizedWrapGrid. Simply adding this to the GridView:

<GridView.ItemsPanel>
        <ItemsPanelTemplate>
                <VariableSizedWrapGrid />
        </ItemsPanelTemplate>
</GridView.ItemsPanel>

seems to do the trick. Perhaps there is a bug in the regular WrapGrid when opening a Windows 8 app project on Windows 8.1? I'm sure the frequency of this is so low it's probably not worth doing anything about it, but hopefully someone who does search for this finds this helpful.

PS regarding making the ListView look like GridView (or vice versa) it occured to me that this would be a nice way to handle changing from filled to "snap" view, instead of having to maintain two separate controls and templates, you could simply relay it out...

I didn't have much luck with this, but it's something I've always wondered about. anyway that's another topic, thanks for your help and attention!