This is a recent regression in the behavior of app requests. According to the facebook blog post (https://developers.facebook.com/blog/post/2012/04/26/android-and-ios--discovery-via-requests-best-practices/), if a developer configures the "Mobile Web" section, their app should get push notifications when requests are sent. This was working until a week or two ago. Now, you get nothing if you have "Native iOS app" and "Mobile Web" enabled. Note - if you also enable "App on Facebook" in the app configuration, one will get push notifications, but that creates the bug of showing iOS app notifications in the desktop facebook experience.