Resolved after much Forum searching..
Parent folders that are created by entering a new path (e.g. newparent/newchild/) have CHMOD permissions 0700 whereas the child or top-level folders created have permissions of 2775, by changing the 'newparent' permissions to 2775 using webmin file manager the shared folder (child) now shows up.
I guess I'll avoid creating parent/child structures using the 'new Shared Folder' dialogue - please feedback if I'm missing something.