“Starting February 26, 2025, the ‘Download & Transfer via USB’ option will no longer be available. You can still send Kindle books to your Wi-Fi enabled devices by selecting the ‘Deliver or Remove from Device’ option.“
Amazon has changed the Kindle delivery protocols, and the USB transfer option is no longer allowed. If you have an older Kindle or Paperwhite without WiFi capability, it can no longer upload books in that manner. For any questions, please contact Amazon directly. This change is not related to the Libby service.