This has been resolved by the carrier

Update from Australia Post:

New incident: Investigating

We are currently experiencing technical issues that are intermittently impacting some of our services including parcel tracking and lodgement, and label printing services. Our teams are working hard to resolve this as quickly as possible. We sincerely apologise for any inconvenience.

We will update you as more information becomes available

Currently, Startrack and Australia Post's Shipping and Tracking API is having issues

We are engaging with the carrier and will advise as information becomes available.