Welcome to the world of commercial reality.
It is my understanding that Avplan used to use the live web feed from OZRunways but don't any more as there used to be stacks of aircraft showing up on Avplan, but now it's few and far between.
There are so few aircraft showing up in Avplan from when I used it, I can't see why Ozrunways would bother feeding them in. Unless I am mistaken, is there a filter that's blocking them out or do they all show up by default?