Hello,
I am running the pre-release software of iOS 9.0 Beta 1 on an iPad Air 2. I have two main Apple ID's I use. One is Australian, the other American. When I try and update an app purchased from the American account, it prompts for the password which I enter. It then does not update the app. When I try again, it does the same, ask for a password and fail. I have tried restarting, changing Apple ID's and resetting wifi networks. It does not work. If you could help me that would be amazing, there seems to be no other occurrence of this on the forums when you look for a search.