It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

Title. Every other integration manages to launch games (even the community Battle.Net integration), but not the "official" Xbox Live integration. Why can't I launch e.g. Forza Motorsport 7 or Horizon 4?
simply the integration doesn't allow at the moment, are just displayable but not launchable, u'll have to wait for further updates.