When I press Run on my Xcode 6.0.1 (latest version at this time), the build succeeds, Xcode logs:
-AppName- is currently running on -DeviceName-
But nothing happens on my device.
You must add your new device to your provisioning profile from the Apple Dev Portal, Devices > Add - use iTunes to get the UDID - then Provisioning Profiles > Select your PP > Add your new device > Download and click it.
Indeed, current Xcode version does not display an error message relative to signing identity.