CSS transition not working in iOS

I have used a sliding sub-header in my app using the same code as this codepen http://codepen.io/danbhala/pen/ChIEt, this works fine in browser with ionic serve but on device the subheader won’t move. I have confirmed the scroll directive is ok by applying a colour change rather than transition and that works ok. I am using ionic 1.1.1 “yttrium-yeti”. Any ideas?