Date Format in a Hierarchy

I have just noticed that our dates are not being formatted correctly in a hierarchy. I have added Date to a hierarchy called Calendar. This is definitely formatted as yyyy-mm-dd. 

However if I add the hieratchy to Axis in a bar chart and drill down I get the following. So the date is mm/dd/yyyy hh:mm:ss AM/PM. IF you drill directly to the bottom of the hierarchy using the connected double down arrow the format is correct but not when you drill down from year to month to date.