[Alpha o]

I just had the same happen to me, but with only 2 books and in reverse.
Calibre cannot see or unlock the books I just bought.

I had some other books changed by Kobo, and since I had them backed up in another Calibre file, they are still intact in the right format. I think most of my books from other places weren't bothered as I had put them all on the card and not into device memory. I did it via the computer. Kobo is not happy, apparently as it says IT will manage the card.

The books that got changed were from the Kobo Desktop library. When it updated the desktop and synced the device, most of the books on the desktop library got changed.

Calibre cannot open nor un-drm it with Obok.

(It is already backed up as an EPUB elsewhere, but since I bought it last year, I don't feel Kobo had any right to mess with a prior purchased product without informing me of any new changes.)