Apparently documents have made the light of day that clearly indicate Tennis Australia gave prospective competitors incorrect information with regard to Australian Border Force requirements.
The Government Department also advised Tennis Australia, in November 2021, that having had a previous infection of covid within six months would not satisfy border entry criteria. The competitor would still have to be fully vaccinated to enter the country.
At this stage three more overseas attendees already in the country are being re-assesed by Australian Border Force as their "approval" also came from Tennis Australia.
Bureaucratic bungling at its best.
Here is an UK article that relates the salient points.