I have a 40-page InDesign document with 2 sections and I'm using a different section prefix for both. I export the full document as PDF and clone it, then I just delete the 20 unwanted section/pages from each. However, upon deleting the continuous pages, for some reason it leaves the last page undeleted and gives an error saying "One or more pages are in use and could not be deleted". This has never happened before. Of course I have to click on the page's thumbnails to select them for deletion. It looks like a very annoying bug.

I've uploaded the error message & version screenshot.