+ AA6YQ comments below
I noticed the same. VK9NA, VK9NP, etc. are all considered Norfolk.
I was not aware of the "fifth character" rule. It seems the Austrialian authorities since then have switched to using the fourth, considering many recent DXpeditions such as VK9MA, VK9CZ, VK9NC etc.
+ If you point me at documentation of this policy change, I will update DXView accordingly.
+ DXView's override mechanism provides a way to handle this inconsistency/ambiguity.