We are currently experiencing issues with the Australian Twitter collection; the volume of tweets collected since 9 April remains incomplete.
We have identified the cause of this issue, and are working to address it at the moment. If all goes well, we should be able to backfill the current gaps in the collection since 9 April once the next full gathering process concludes, and I will update you when this has happened. There is a small chance that some gaps in the collection may remain for those accounts that have tweeted more than 3,200 times since 9 April; we would expect this to affect only a very small number of extremely active Australian accounts, however (mostly bots and other automated accounts).
Apologies for the inconvenience, and there will be another update once the next full collection has concluded.