Kindle library on iPad: How to access?

I am unable to access the list of titles in my Kindle library.

Up until a couple of weeks ago, I could access them when I finished whatever book I was reading. I tapped on the top of the page on the left-hand side, and the library list became visible. Then that stopped working.

At first I tried by shutting down the iPad, so that when the iPad reopened the library list would be immediately visible. It worked well a couple of times, but no longer. I can't get to the library either by shutting down the iPad or by tapping on the top of the page.

I hope someone can advise. Thank you. :)