Ok, somehow I solved it…
After this morning's update and reinstall of the package, the menù and service was still not there.
Since I have two pfSense machines (the primary is stuck on the updates before the Snort retire and update) I could compare the config files to see what was wrong...
In config.xml of the secondary machine there were missing:
Node Service <name>snort</name>, ...
Node Menu <name>Snort</name>, ...
I just added those two items, and now everything is working... if you need to investigate on why the package installer was unable to add this two nodes in the config files I can send the log files or all the info you need...
Thanks a lot,
Michele