Why is an MSS user with subordinates unable to reassign their inbox items?

Why is an MSS user with subordinates unable to reassign their inbox items?

Enable the "Remove ESS permissions and default to company-level permissions to allow company-level users to edit their own profiles" checkbox on the Security Setings screen. in order for  an MSS User to have the ability to reassign inbox item.

      Navigate > Configuration > Security > Security > Secuirty Settings