It appears that the collection book bugs out when navigating between the Arcade tab and the Fishing Tab. If you click on a sub category in either of the tabs then click on the other tab the index buttons will no longer work.
How to replicate the error state:
- Open Collection Book and go to the fishing tab.
- Select a sub category (e.g. Fish, Other Marine Life, Adopted Animals, etc.)
- Change to the Arcade Tab by clicking the bookmark on the left.
After clicking on the arcade tab you should see a blank page with only a Back To Index button at the top and a bar at the bottom saying Page 0/0. If you click on either ‘Back to Index’ button at the top or the Fishing Tab you will be returned to either tab’s index where the buttons will no longer function.
Closing the your book and re-opening it will resolves the issue. However it will present you the last page you were on before entering the error state (page selected before step 3).
Here is a video of the bug in action: