Today I realized a couple of 1550s stopped logging.
They are running R81.10 and those two firewalls are in a VPN community along with another identical firewall that doesn't have the logging issue.
Traditionally, modified the masters file to replace the hostname of the CPM with its external IP address, also added the CPM with the ext IP to the /etc/hosts file and froze the define_logging_servers and use_loggers_and_masters by setting them to "false" in GUIEDEDIT
Then saved the changes to the DB and opened SmartConsole R81.20 and pushed the policies, the content of the masters file got overwritten therefore the logging issue didn't get resolved.
It might be useful to mention I faced this issue with every firewall we recently upgraded (replaced the appliance), which includes the 3000 series with R81.20 T631
Your kind advice on this will be appreciated, I cannot troubleshoot other connectivity issues without logging.