I just had this same problem. go to tools > folder options > view, and under hidden files and folders, click on show hidden files and folders. then click okay. then delete those hidden files, which were written overtime and stored onto the usb without your knowledge. the usb will have full memory space after you're done :)
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I just had this same problem. go to tools > folder options > view, and under hidden files and folders, click on show hidden files and folders. then click okay. then delete those hidden files, which were written overtime and stored onto the usb without your knowledge. the usb will have full memory space after you're done :)