As the title suggests if you are in the collection book looking at the fish
and then switch to the arcade tab before pressing the back to index button
The book will break, and you cannot use the buttons inside the arcade or fish tab anymore
(This can also happen if you start on Arcade and go to Fish before returning to Index)
The only way to fix is by closing and reopening the collection book.
Not a major bug but still wanted to point it out nonetheless.