I've wasted a lot of time trying to get Unity 2019 versions and iPhone 7 to work out of the box, the camera does not seem to work in any of them and some others give a pink or black screen.
I moved back to Unity 2018 lte version and tested the default Astronaut card and this works but importing my own image targets database from the Vuforia uploader tools fails to show my models and gives errors. All looks good until I get it on the iPhone, the astronaut still works but the custom image targets fail. I replied to a previous error thread but don't expect anything from its long list of same issues.
I have no problems on Android phones for 2019 and custom databases