Problem converting music to USB

When I transfer music from Rekordbox to my SanDisk USB and plug it into a CDJ-2000, the player fails to read the USB and prompts me to format it. Despite formatting the USB multiple times to FAT32, the issue persists. Even with other USB drives—including a brand-new one that should work—I encounter the same problem. This has happened with multiple CDJ-2000s, yet my RX3 standalone setup at home reads all files without any issues.

Can someone help me???