It has taken a couple of months but I clicked the publish buttons on iOS and Android yesterday and … it turns out there was an #IFDEF DEBUG section that I had forgotten about. So, Apple politely informed me it wasn’t working and a quick rummage through the crash log told me why. Resubmitted it with an updated android version as well. They hadn’t mention ed it was broken but it would have been.
Then there was an issue with M$ AppCentre. This handles analytics and crash reports for your app. The Android version worked fine. The iOS worked fine on the simulator and my devices. When Apple installed it though it crashed. Turns out I was using the Xamarin method of starting the appCentre rather than the Xamarin.Forms method. It took a while to re symboilize the crash logs but once I had done that I could see where the problem was.
As I speak, both apps are live in their respective stores.