Re: "Known Good" USB stick for Unetbootin?
It may not be the USB stick -- it may be unetbootin.
I tried using unetbooting to create a bootable USB for 12.04 -- and while the app said it worked, the USB stick would not boot.
So, I tried again, using the same USB stick, but this time, with the Universal USB Installer, downloaded from PendriveLinux.com.
This time, using the same USB stick, it booted just fine.
Ubuntu 16.10 Mate, Mint 18 Mate; MS Win 8.1, MS Win10 Pro.
Will not respond to PM requests for support -- use the forums.