Scrollviewer and Semantic zoom not working together

Hi James,

I have sliced out the relevant code from my project and have kept here "http://ift.tt/1qVdwzc;. Please append https:// to the link as I cant post a link here for some reason.

You can run this project and see the issue.

Please let me know if anything else is needed or if I am doing something wrong in my code.

Thanks,

Sanchita