While there is only one specimen of this suggested species on the ALA and three set specimens on BOLD Systems 4 from Victoria (Gippsland) I am suggesting this species because the markings appear similar.
Distinguishing Isochorista species is a challenge. There are 6 named species that have ACT specimens at ANIC, plus at least one unnamed species. Several closely resemble the photo and others, like I. ranulana, are different. I. pumicosa has highland specimens from Snowy Mountains and Brindabellas. I acrodesma has plenty of ACT lowland specimens, and I think is the most likely for this report. But Isochorista sp is safest.
OK, a diverse genus its seems locally, but not yet well documented in the public domain. But from what I can see online I. pumicosa does look quite a good match.