Trouble Tickets - notifications not working

Hi all,
I've been using v.17 for a long time and now I've installed v.20.04.
It seem to run fine, but maybe there is a problema with notification of changes in tickets,
It seems not to be sendmail problem, other communications goes, and I receive smtp test mail when I change smtp settings.
This is a test mail sent to confirm if a mail is actually being sent through the smtp server that you have configured.

I also tried my own smtp-server and no messages arrived in the queue to be delivered when someone create/update a ticket.

In my account profile I have set

NOTIFY ME VIA : email

and in 14.NotificationSettings I have all fields checked as NotifyTheCreation+NotifyTheChange

Finaly, in crontab I have this line
*/1 * * * * root /var/www/html/cron/RunCron.sh >> /var/www/html/logs/cron/cron.log 2>&1

So, I go to TroubleTickets + Create + assign to a colleague + SAVE
... wait but no message arrive, and no messages are sent to the smtp server
Then, I reopen it + assign to me + set as URGENT+ SAVE
... wait but no message arrive, and no messages are sent to the smtp server

If a sign-out/sign-in I don't receive any notification on screen, for the updated ticket.

I'm reading all *.log files inside installation folder, but cannot see anything relevant.
Can I increase level of verbosity? or enable a debug-log?
What can I try?
Any advice?

Thanks in advance.

Alex