Comment 13 for bug 1173457

Possible workaround: (instructions are for macs, but the idea of starting ubiquity with:

ubiquity --no-bootloader

might lead in a direction to a workaround for PCs. If you figure out a full solution, please post on this forum as I'm monitoring it and it looks like people are starting to find this bug report from Google after much agony).

https://medium.com/@mmiglier/ubuntu-installation-on-usb-stick-with-pure-efi-boot-mac-compatible-469ad33645c9