Perhaps this is what's going wrong for me. A week or two ago, if I downloaded a personal doc book from Amazon to my Voyage, then in Calibre, copied it to the library, deleted it from the device, changed the metadata (including the cover) and sent it back to the device, the cover would show up (as well as any changed metadata) and syncing with other devices (so highlights, etc. show up) worked. I tried it with another book today and it doesn't work. It's an AZW3 file (the file that Amazon sent to my kindle, which I copied to my library then sent back to the kindle) and sending it to the kindle from Calibre doesn't show the cover. Any fixes? I liked having notes and highlights sync, but also like having the covers.