So, what happened in Count Pages.
I created a 'book' by adding a CBZ file to a calibre library in which there were almost 200 books with a lone CBZ. But for this 'book' I had a number of small MP4 video clips (animations) I wanted to store with alongside the CBZ so I put them in a RAR and added that to the book.
I then ran the Count Pages (CP) plugin - it didn't update my Pages/#pages custom column
It had worked on every other book in that library - difference was none of them had a CBZ and a RAR. So I opened the book folder and renamed the RAR to BAR, and ran CP again - the page count column was updated. I then renamed the BAR back to RAR.
I reported the issue in the CP thread.
When a new version of CP was released, the problem was still evident; assuming it had been overlooked (there had been a flurry of other posts immediately after mine) I posted a reminder.
The response was "Your problem is caused by you using .RAR files - quite simply, don't
".
So I renamed it back to BAR, set Windows to open BAR files with WinRAR, and added a bar.png (WinRAR's icon) to %AppData%\calibre\resources\images\mimetypes.
Which made me think - why not have a calibre tool that can create a zip-like container for a book with a fixed name, e.g. book.attachments (a'la cover.jpg & metadata.opf) with options for basic file operations (add, delete, rename, OS open with), and maybe move files from the book folder into the book.attachments archive and vice-versa. And unpack to a folder and pack a folder as an book.attachments container.
Could it be a plugin. Have to dash - again. pacemaker grease and oil change.
BR