Comment 21 for bug 1589028

The problem is that some tools do not recognize the hybrid iso file's internal structure when cloned to a USB drive. This has been a standard for iso files that can be cloned to CDs, DVDs and USB drives (actually any mass storage drives including memory cards SSDs and HDDs).

The Ubuntu Startup Disk creator is only doing the cloning job like several other tools and should not be blamed for this problem.

Fortunately new versions of gparted can recognize USB drives that are cloned from hybrid iso files.

There is an easy fix, if you want to use other tools: mkusb has a dedicated menu option to restore the USB pendrive to a standard storage device,

https://help.ubuntu.com/community/Installation/FromUSBStick#Postrequisites_-_restore_the_USB_stick