No discount price

The Minecraft discounted price offer is still valid (I believe the discount is permanent for owners of the Xbox 360 edition of the game).

As for the discounted price for Australian buyers: the price should be about 25% of the original price (75% discount).

If you're comparing the 2 prices shown on the store, the first price is the discount for non-gold members, not the regular price. So you're just seeing the difference in price between the gold discount and non-gold discount.

Have you played the 360 one recently. Try playing it and waiting 24hrs and then try to buy the One version.

I downloaded the discounted version on the Xbox One last night, I had the disc copy of Minecraft on the 360.

As you said a fix is in the works, right now for whatever reason only people who have the digital version of the game are being offered the discount. Just give it a little while and keep checking to see if it changes.