|
I assume the missing covers you see are solely in Device View in calibre? That information is stored in a file called metadata.calibre on the Kindle drive -- it caches all the Device View information, the cover is a base64-encoded thumbnail -- and sometimes it can get corrupt, also calibre will clear it if it detects the book is no longer there. If calibre was partway through updating the file (it resends the whole thing) then it could have been corrupted -- next time you connected, calibre rescanned and added all books, but with only the basic info that gets extracted in that case, not the enhanced set which calibre sends during send-to-device.
If you right-click on a book and select "Match book to library" you can tell calibre a specific book goes with a specific calibre record. Then select the Device dropdown in the toolbar, and "Update cached metadata on device". It will update all the metadata that fits in Device View, including the cover thumbnail, series info, tags.
|