This has been a known problem since the firmware update that changed the Scribe to use MTP instead of USB block device mode. There is no fix yet. The only way to get covers right now is to upload to Send to Kindle, or set up KFX Output and be sure to tick the PDOC config option when converting and then send the KFX over USB.
https://www.mobileread.com/forums/sh...d.php?t=355951