I've always had too much rendering from ViewCell to WP8.1.
I wanted to do the same thing as you, but I read in too many places that a scrollable component inside another scrollable component never gives the desired result.
Instead, I choose to use a single ListView. When the main category is used, load the list view into subcategories. To go back, you can have a subcategory of "..."
Add the GoBack subcategory to the list before adding other subcategories. 
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