Startrack has marked this issue as resolved

As per Startrack / Australia Post:
a fix has been implemented and they are continuing to monitor impacted applications for any further issues.

Australia Post has advised:

A fix has been implemented and we are monitoring the results.

Australia Post / Startrack has advised:

The issue has been identified and a fix is being implemented.

Please see the comment below from Startrack / Australia Post

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

Updates directly from the carrier will be available from the below:
https://status.developers.auspost.com.au/incidents/89vgfrhl7knv

We will advise clients as more information becomes available