All my custom created policies for ENS Threat Prevention disappeared. I restarted both ePO server and its database server, but they are still gone. ENS ATP, Firewall and Web Control; custom policies are still intact. I'm using ENS 10.6.1.
Do you have backup of your policies? I would suggest importing the backed up .xml files. It seems your policies cannot be seen anymore. Try opening a ticket to support for the root cause.