one book not syncing with Calibre, now no longer shows as on device

[BlackDogWhite]

KOReader on Kobo Libre Color

I have one book out of many that would not sync progress back to Calibre when using KOReader Sync plugin.

In trying to debug the issue, I grabbed the KOReader Metadata Sync output and found the book in question was not listed in the results - even though the book was on the Kobo.

I "read" a few pages on a couple other books and they synced OK. So I deleted the book from the Kobo using Calibre (right clicking the book and selecting Remove books->remove all matching books from device; and as an aside, I sure hate the verbiage used on the menus in Calibre - I'm not ever completely sure I'm just deleting a book from the attached device and not deleting it from the library!).

Then I detached the Kobo from the computer/Calibre using the Device menu in Calibre, waited for the Koreader to reboot, reattached to Calibre, saw the book was not there, and added it back in, detached, reattached, and now the book does not show in Calibre as "On Device" even though it clearly was.

So I repeated the delete of the book and also deleted the author directory on the Kobo (using computers file manager); detach, attach, add book back in, still does not show. But the book is on the Kobo; I can read it, and I can see the folder in the file manager.

Any thoughts on what I'm doing wrong or how to debug? It's really not that big a deal it is nice to have the progress sync. Also I don't want to let the problem get worse.

[BlackDogWhite]

I'm not sure if this is relevant but I also notice a book on the Kobo that apparently has no UUID. I removed that book, but upon the next sync saw there was another without UUID.