Shaina maple scorched leaves, no signs of autumn colours

What am I missing?

I’ve had this Shaina Japanese maple for about six months now. It is potted, and sitting in my courtyard which is facing northeast. It gets mostly mid-morning to early afternoon sun, between 3-5hrs direct light. It’s not looking great with scorched leaves and some turning brown and falling off. It is also not yet showing signs of red coloured leaves despite us being in the middle of autumn already. Location is Western Sydney, Australia.

Any tips how I can reinvigorate this tree?