I tried to add a new instance for AUDIT.FILTER class and noticed that the option is disabled. Are you also referring to the same issue?
if so then to solve the issue I edited the FILTER class and changed the "type" field to "Configuration". This change enabled the "New instance" optoin. You can try the same if you feel will help in your case. Please check carefully as editing a ClASS will impact all the connections.
I have attached a screenshot showing the configuration change.