Crashed in Xamarin.Forms iOS app running 12.0.1 & ip version 6

I recently added the plugin to one of my apps. It works fine on my iOS 11.3 device. It crashed on startup when Apple was testing the app. They used an iPad running version 12.0.1 and ip version 6. Not knowing what happened, I commented out the initialization code and it passed Apple's test. I'm using the latest version of the plugin. 