Ann: Production Update and FY 2019 Guidance, page-23

Calm down. Imagine if they announced the disruption before they resolved it in early/mid March. "We are currently experiencing a reduction in our equipment availability at Westralia. We are yet to resolve this disruption therefore impact to the march quarter production and AISC is unknown." Perhaps management decided this would prove more damaging short-term and wanted first to resolve the issue and evaluate its impacts.