Have you tried formatting with the tool SanDisk recommends?
http://kb.sandisk.com/app/answers/detail/a_id/19258/~/formatting-usb-drives-with-third-party-tools
Have you tried formatting with the tool SanDisk recommends?
http://kb.sandisk.com/app/answers/detail/a_id/19258/~/formatting-usb-drives-with-third-party-tools