Config filter host parents and exclude host parents via UI is the New feature in 6.6.
Created redmine issue https://projects.theforeman.org/issues/27553 from this bug
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2019:3172