In my experience, this has been caused by one of two issues. First I'll offer solutions to a potentially broken installer (which I've experienced a few times over the years). Then I'll comment on the Installation Media's format at the end.
One possibility is a bug in the Disk Partitioning by the Windows installer, in my experience. Over the years I've seen it either utilize the wrong sector sizes or, more commonly, not set the boot partition as active. This is assuming that the failure occurs AFTER the partitions are setup which has been my experience.
To repair this, after Windows Installer sets up the partitions and fails to install, please try the following:
1) Boot with your Install drive mounted and go to the "Repair Options" section
2) Open a Command Line
3) Then type "diskpart"
4) Verify you only have the one drive by typing "list disk"
5) Type "select disk #" with # being the disk you're installing to
6) Then "list part" which will give you a list of partitions on that disk you have selected
7) Type "select part #" where # is the boot partition that the installer created but failed to install to
8) Type "active" to make that the active boot partition for this device
9) Type "exit" to finish with diskpart and let it save the changes
At this point you should be good to reboot and attempt the install again.
If at this point you're still out of luck, it is likely the installation media you are using. Since you are using a GPT USB drive, it could be conflicting with the installer's attempt to locate proper installation destinations (even with you explicitly stating yours). To remedy this, format the drive as MSDOS (good ol' FAT32) instead of GPT and try again.