I can vaguely remember a similar problem reported here on the forum with cause being the USB formating type (exfat/ntfs/etc). Please try searching using keywords, I am not able to do it at the moment for you.
How did you format the usb stick? What software, what settings?
So i tried some things and it’s now working ^^
Here’s what i did :
1 : Formated my USB stick with MBR via the Disk Manager on MacOS, as @djliquidice advised
2 : I removed all numbers and special characters from the key name. Originally, it was named “Wassay #1”. Now it’s “WASSAY-A.”
I think the problem probably came from the name of the key, knowing that other DJs were using FAT32 keys in GUID without any problems. The character ♯ was probably causing recognition problems…