无法通过Xcode Organizer / iTunes安装iPhone App存档

I have spent quite some time trying to resolve the following issue: We use to give xcode-built products (OurApp.app) to our customers for testing (they usually then drag them on their test devices via iTunes). Of course, all those devices are enabled for testing, i.e. added to the provisioning profile we build the app with. This has been working fine for some time.I have spent quite some time trying to resolve