3D FlipBook - Hi Guys, I like this plugin is very easy to work with. I have a problem, suddenly stop showing the books just appear

Hi Guys, I like this plugin is very easy to work with.

I have a problem, suddenly stop showing the books just appear “Please wait the application is loading” https://www.screencast.com/t/pFt0qPCtuMAO

And when i go to edit any of the books appear “Please wait! The book is processing…” and stay there, doesnt load the book and neither the thumbnail https://www.screencast.com/t/BjFjHt6y3HJ

<p>What can be the issue</p>