So I tried the unreleased 7.01 version and it works.
Nope, gNewSense does not appear to work either.
Wasn't Trisquel going to be moved to being based on Debian?
No but it was based on Debian in the ancient past. (gNewSense did transition
vice versa)
For some reason the workaround at
https://bugs.launchpad.net/ubuntu/+source/casper/+bug/1241589/comments/55
does not work for me. At the prompt I cannot find a device for my USB stick.
The only device found is my harddrive at /dev/sda.
So I finally setup a CD drive and a CD and it doesn't work like it does in
the guy's video. First of all it is not recognized in the Boot Manager menu
in UEFI mode and second of all it fails with the same Unable to find a
medium containing a live file system error in legacy mode.
Nevermind.
It seems that legacy boot mode was buggy but that UEFI boot mode with secure
boot disabled was not buggy and works.
So the problem only appears to affect Ubuntu based distros
https://bugs.launchpad.net/ubuntu/+source/casper/+bug/1241589/comments/61
Wasn't Trisquel going to be moved to being based on Debian?
In any case, I guess I can use GNewsense for now.