Manager user limited only to subset of resources on second level of document tree cannot see them unless top level document (their parent) is included in the group of resources. Why?

Thanks for all advices. After I have upgraded to new version 2.2.10-pl all works right. Originally I had version 2.2.7. Still I must add parent directory to new document group and then assign to user group with load,list,view permissions, but combination of tree_root_id and ACL works now.