Open AppStore from website link in IOS 9

I have a webpage that includes a link to 'Download from the AppStore' which I want to either open the AppStore app if tapped on a device or open the Apple Itunes page for the app if clicked within a desktop browser. I am not trying to open the app itself by using myApp://, just want to open the AppStore download page.

I have this working fine for iOS8 (and lower). The AppStore app is opened and lands on the app page itself. On iOS9 however an error message is shown when tapping the same link: "Safari cannot open the page because the address is invalid".

On the webpage I am using a simple a to link to the appstore page like so:

<a href="http://ift.tt/U4iR6e" class="appstore-base" target="_blank">

Note: I have replaced my app with Twitter for this example, URL format is the same.

How can I get this to open the AppStore on iOS 9?