When you connect a USB memory device, an icon is not automatically displayed on the printer control panel. Select USB File List from the Settings menu, or transmit data from a computer to the USB memory device connected to the printer.
Make sure files on the USB memory device are saved in the root folder. Only prn files are displayed when the device is connected to the printer.
Also check the Job History setting in the Garment Creator software. If all of the jobs are being stored, there may not be room on your computer's hard drive for new file printing.