In Power BI Desktop Jan 2018 release, with a Date or Date/Time field selected in the Fields pane, when you navigate to the Modeling ribbon / Format / Date Time menu, the options at the top (marked with an *) that respect the machine locale now show in US format (e.g. M/d/yyyy) on machines with non-US locales e.g. English (Australia).
This appears to only be a problem in the display of the menu. When date fields are shown in a visual e.g. a Table, the expected non-US locale is used e.g. d/M/yyyy.
This issue was introduced with the Jan 2018 update to PBI Desktop.