Defeating Good Security

So I use randomly generated passwords that are long and contain numbers and special characters. I also use 2-factor authentication. So I copy my password from password app, enter my email, paste my password, hit comtijue and am prompted for my 2-factor code. I minimise the Google Books apps, grab my code come back and oh... Back to the start. I cannot leave this app without having to start fresh every time! I have no idea how I can log in?!

clearnew about Google Play Books - Books & Comics, v3.1.1