iphone Are you able issue

So I think this camera app work great with the with the product I purchased however the only complaint I have is that on any iPhone from seven or above every once in a while you’ll hear an audible tone like something set off your camera and when you go to look at your phone there’s no notification nothing was ever triggered it’s a mystery so you have to leave the sound off otherwise you can get notifications if there’s movement in front of your camera and the rest of the app works fine