I’ve created role which can see and edit specific dashborad, it works fine if you choose dashboard from “Dashboard” menu. But if you go directly to dashboard by link e.g. “https://graylog.example.com/dashboards/5e67a53dfaa4790027df94c9” You will get “Not found page”, even if user is authenticated. I don’t have this problem if logged in as “Admin”.
OK, solved, the user was assigned to another LDAP mapped role as well (because it was default user role) which has no permissions, so looks like it override the right role permissions, I’ve removed that role manually and set up to use built-in “Reader” role as “Default User Role” in LDAP configuration.