Please make sure the device updated to 3865 firmware release. https://cymaticaudio.com/images/downloads/manuals_and_brochures/Cymatic_uTrack-X32_FirmwareUpdateGuide.pdf
The USB drive must be formatted with uTrack-X32 before you export the content to the drive.
Is that a USB HDD; SSD or USB stick?
If you still have this problem please try with another USB drive.