The beta iOS may be conflicting with the current application. Since it is beta, putting an app update for it to suit beta may break it for those on previous iOS.
I think I saw a kaw update for iOS 9 a few days back. Check to see if there's an update for the game.
Check your iOS version under settings--> general--> update Give me ss if your on iOS 9 and your app running ok on iPhone. Devs said they are aware of issue and they are working on it. If anyone find a way to fix it share here please.
Can confirm this happens on my iPhone 6 Plus with iOS9 Public Beta 1 as well. Keep in mind that iOS9 is a BETA at this point and that things WILL break with a number of apps. You should never use beta software on a device you NEED to function properly at all times. While we will definitely get this fixed by the time iOS9 is actually live, it probably won't be fixed immediately as things change between each iOS Beta. Something that is broken in one may work in another, and vice versa.
It would not break anything for anyone on a previous ios as it would run different code depending on which iOS u are on however they may put off a fix bc the next update of the beta may break it again.
Like someone else said, they probably won't attempt to fix it until the official release of iOS 9. And that is if it is a bug on their end, it still could be possible that it is a bug within iOS 9 since it is in beta stage. I suggest restoring your phone if you can.
In the future the best way to have direct contact to the devs is to email them, not use feedback. If you need the email, just ask