It's quite simple - you specified NORTH, EAST and WEST within the section access and therefore the used wildcard * will fetch them. Not specified values or NULL won't be included.
You could imagine section access as a kind of selection - in this case like (NORTH|EAST|WEST) within a listbox and therefore a non-specified value like SOUTH isn't included (the difference between a selection and section access is that the non-matching values - and their associated vales - aren't just excluded from the current calculations else they are completely erased from the datamodel).
AFAIK you could bypass this behaviour with dummy-entries like:
