I added a couple of new books this afternoon, so I selected one of the ebooks without the cover display. I hit "Match book to library", and it came up blank. Thinking "Oh hell, no" I hit search, and it found the book. THEN the cover updated, and a little message said "please update your metadata on the card/device". Which I did. I promptly tried to do it with ALL the ebooks selected, and a little message said "Please select only one book". When I have the time I'll go back and do it for the 1/3 of the books that don't have the display covers.
What I don't understand is this: when I plug in my Kobo, the books that are on my device and card have little check marks on them (cover display) or next to their names (list display) when I'm in one of my libraries. When I look at the card view, little green check marks are next to each title. So why does the "Match book to library" need to be specifically done? I would have thought the little green check mark would imply it found a match.