REKORDBOX : amovible media is corrupted

Hello PIONEER team,

i got a problem to export library on USB device (8GB memory key) i've never has before.

loading from REKORDBOX to USB device works correctly (it appears correct), and after loading, if i browse with computer, i found PIONEER and CONTENTS folders. This is OK.
I unplugg USB device from computer (with button eject in RB to play it on my CDJ (850), and it is catastrophic :
- no BROWSE, no PLAYLIST, no BPM, no GENRE and other option. Only classic browse is available (like a USB with only files on it).

I replugg it on computer to check what mistake i did, and RB display : "amovible media is corrupted" and don't display it into explorer.

I formated many times (FAT32), with no result
I updated RB to the lastest version, with no result

What is the problem which could provoke this ?

i hope you have understand my problem, my english is poor.

thanks