Kindle App for iOS

I use the Kindle app on all of my iPads. (For that matter, I also use it on my Android devices.) Reading, and in particular books, is probably my main tablet use case. Consequently, the Kindle app is mission critical.

On 2018-12-05 I upgraded my iPad Pro 10.5 to iOS 12.1.1. Later that evening I tried to open the Kindle app and all I see is the "cursor" spinning with the Kindle app window display.

For now the Kindle app is working on my iPad Mini 4 but I did not upgrade it to 12.1.1 for fear that it is what is breaking the app.

Something was wrong with my iPad Pro 10.5 and I ended up doing a factory reset and restore. The fact that I had problems doing the reset indicates to me that something had definitely got messed up. Now, if I upgrade the Mini will that break the Kindle app too?