@FCCL-Vandoeuvre This sounds identical to the issue I had. Basically during the imaging process, it would stop and show Starting sshd: touch: cannot touch ‘/var/lock/sshd’ : No such file or directory along with starting deployment scripts. I knew it was firewall related because when I disabled the firewall rules, it would work.
It turned out the solution was to configure NFS mountd to use the static port of 20048. You mentioned doing something similar, but I modified a different file than the one you mentioned (nfs.conf). Below is a link to the forum post I made and the solution.
https://forums.fogproject.org/topic/17604/what-ports-does-fog-use/2?_=1724085771324