From the ATSB website today (bolding is mine):
https://www.atsb.gov.au/publications...r/ao-2017-118/
Update published: 31 March 2020
The ATSB investigation into the collision with water involving a de Havilland Canada DHC-2 Beaver aircraft, VH‑NOO, at Jerusalem Bay, Hawkesbury River, NSW, on 31 December 2017 is continuing.
The ATSB external review process commenced on 20 December 2019 and provided directly involved parties (DIPs) the opportunity to comment on the draft investigation report and present any evidence in support of their comments for incorporation into the final report.
During the report review process period, some additional evidence was obtained by the ATSB that requires further research and analysis to ascertain its relevance and influence on the accident.
This has required an extension to the intended timeframe that the ATSB will be able to complete the final report. The ATSB intends to complete this analysis and provide DIPs with the opportunity to consider and provide comment on the new information if deemed relevant.
The additional work is anticipated to be completed in the second quarter of 2020.