As the title says, apparently this can be an issue if local prices haven't been set as well as the normal price. Could it be that you haven't set an AUD price or are you only selling on itch.io now?

Thanks :)

There's still a price and a buy button in USD with a US location.  (The current non-sale steam price is half of what the price is here or I'd point out that devs get better compensation from itch and strongly suggest that you  buy here.)