The site has never worked with ios 9 and likely never will. The version of Safari that's included with it is prehistoric in web technology terms, and the features which minimise network usage and allow to work more like an installed app just don't work with it (or Windows mobile 8.1). OTT is older and was created in the first place with more basic technology, so it continues to support more dated browsers.
At the end of the day, Apple are the ones tying Safari updates to ios updates, whilst preventing anybody else from writing a browsing engine for ios. Android is far better in this respect, and because Chrome is a separate app Traksy continues to work with much older devices on this platform.