InterContinental Hotels: Priority Club & Inter-Continental Ambassador - Are Plat (Amb) Room Category Upgrades Standard at HIs in Oz?

Specifically Brisbane and Cairns....I'm wondering if we can reasonably expect a one-category upgrade if the higher category rooms aren't sold. Thanks....

I stayed in Cairns recently & booked one above the basic room. I was upgraded one category (to seaview) without asking & to one of their trial refurbished rooms.

I've stayed a few times at HI Brisbane and always been upgraded with Platinum. Never been to HI Cairns.