Sample: https://storiesonline.net/n/27344/the-library-of-ibados/23
Currently 4 page of comments, clicking on page 3 or 4 make page 2 not selectable
Second sample: https://storiesonline.net/s/17158/sam/33
Currently 7 pages of comments,
After going to pages 3,4,5,6,7, you can't select page 2.
Also when you are on page 2, the appearance of the 2 button isn't the same as any other page when selected.
As a workaround, returning to page 1 makes page 2 selectable again. (I expect you realised that but others might not.)
AJ
Weird.
I tested on the site and it behaved like you described. The page '2' button was not being created correctly.
I decided to fix it and I started by testing on my development machine and it behaved as expected.
I re-uploaded the code from the development machine to the live site and now it works as expected.
It seems like a bug that I had fixed few years ago and somehow the code never made it to live site.
So: Fixed!