Attempting any scan of QR or Bar code does not work on Iphone Ios App ver 12.0 You do not get to see the camera view, just a white screen. This was working fine in earlier versions, it seems a recent update broke it.
According to this thread, a new fixed version will be released in the next 2 days.
Having the same issue currently w an iphone 6 with the most updated version.
We've just released version 12.6 that includes a fix for the QR scanner.
Please update the version using the App Store.