The Kindle edition of Pool of Radiance (ASIN B0076Q1EBA) is incorrectly listed as 31 pages. This appears to be a truncation error on Amazon. The paperback version of this book is 316 pages, and I just purchased the Kindle edition - it's much more like 316 pages than 31. Please update the page count for this edition to 316 to reflect correct reading stats, thanks!
Since Amazon lists the Kindle edition as having 31 pages, Goodreads must use the Amazon page count as the source.
You could try reporting wrong information on the Amazon page. If they correct it there, then Goodreads would be able to match it. [and if you do, may the force be with you...]
Link to paperback version showing 316pgs:
https://www.goodreads.com/book/show/2...