With iOS 11.1 or newer versions, there are camera-issues with web applications added to iOS home screen. While the camera opens, it stays black and image cannot be taken. More information about iOS Bug here.
NOTE: with iOS 11, we do not recommend adding app.audits.io to the home screen.
SOLUTION: instead of opening audits from your home screen, open it in your browser by navigating to app.audits.io. In your browser, camera works just as usual.