I have three iOS7 phones to hand (5s, 5, 4s). On all three, if I set the camera flash to "on", and take a picture, the flash only fires if I take the picture with the screen button, and never if I take the pic with with the volume "+" button. Is this design or bug or fault? I never noticed this on iOS6 but don't use flash much so may have missed it. Can anyone else try this out please?