If you look in the Collections panel, do you see your "Saved Book" Collection? (It will have a small icon that looks like a book)
"Team"- we are just other 'users' here but like 'working together'.
Thank you for your kind help. After placing my question I realized that it is a user forum, rather than a support chat managed by adobe. Doesn't really matter.
Back to topic, my saved book collection is visible. A small book icon and the arrow that only becomes visible when the cursor is placed over it to open the book. I can open the book, however, it does not display my book, but an empty book with an arbitrary layout. Unlike when generating a new book, the empty book displayed cannot be saved as a new book. It looks like my book was replaced by this empty book, however, the thumbnails of the pictures in my book still display and display the little black tag with the number of occurence in the book.
Any further idea?
I had a recent glitch also- a small book re-opened with 51 pages auto-filled with the same photo filename but the pages blank.
So I don't have an answer to your 'glitch'. It is a strange one.
Suggestions (each more drastic)-
Right-click the Book Collection to create a Duplicate to use for experimenting, then 'experiment'.
Open a recent Catalog Backup to see if you can find a working version of the Book. (You may be able to Export and Import "As a Catalog" to restore the Book from the working version.)
Reset the Lightroom Preferences.
Re-boot the computer.
Update Lightroom with the 6.12 update (no need to un-install first)
Run Adobe CC Cleaner to 'clean' and un-install 'selected Adobe programs' , then Install Lr Application v6.0 followed by v6.12 Update.
Most of the suggestions I already tried, no success.
But I did not yet restore the book from a backup, my most recent backup is 5 days old, most of the work potentially lost was done after this timepoint. My concern is not only about this book, but also about future projects. How can I avoid this issue in the future? If this threat hangs over each book like a sword of Damocles, I would consider changing to another application, at least for book printing.
And I did not yet update to 6.12, I still await a response from Adobe. If this should be helpful, I will definitely let you know.