No need to have Persons in both Report and Domain trees.

bt5/erp5_project/SkinTemplateItem/portal_skins/erp5_project/TaskModule_viewTaskList/listbox.xml

@@ -236,10 +236,6 @@
                           <string>region</string>
                           <string>Region</string>
                         </tuple>
-                        <tuple>
-                          <string>preferred_group_person_list_domain</string>
-                          <string>Persons</string>
-                        </tuple>
                       </list>
                     </value>
                 </item>

bt5/erp5_project/bt/revision

-807
\ No newline at end of file
+808
\ No newline at end of file