Hi chris,
Don’t ask me why, but yesterday I tried for the last desperate time and it worked. All templates where there, and all default Vms got installed.
The ISO was flashed on the USB drive with the dd command in linux environment.
I tried to use the last USB drive that I never used before to install.
The main difference with the previous times was that during the initial setup (post-reboot phase) I left the USB drive inserted. I don’t know if this is the problem.