I'm running into similar troubles as you @squish
the '/root/udisk' folder is empty when I serial into it. I can't even seem to find where the mass storage is mounting to. I have tried to do a find for a file I put into the payloads folder.
root@bunny:~# ll /media/
total 8
drwxr-xr-x 2 root root 4096 Feb 9 2017 ./
drwxr-xr-x 22 root root 4096 Dec 31 16:00 ../
root@bunny:~# ll /root/udisk/
total 8
drwxr-xr-x 2 root root 4096 Dec 31 16:10 ./
drwx------ 6 root root 4096 Dec 31 1969 ../
root@bunny:~#
I'm wondering if it didn't get flashed properly and if there is a was to re-fla
