Am working on a fix for this now. Should be live on the site later on today or tomorrow.
There was a bug introduced at the end of October that caused this. The problem is that the DB query to get the page count is joining items and purchases together – so it’s counting out the number required based on items X purchases, instead of just items.
Will post when it’s live.
Fix is now live.
Have a look and let me know if anyone sees any problems still