Sorting "" properly for date formatted column

I see what is happening. I left a few blank rows and filled the formula down....the result was that the filter reverted to A-Z type sorting. If I entered a date after the blank area, the filter again reverted back to Oldest to Newest again. It is an oddity that the blank cells if not "bracketed by dates" (date entered after the blanks) will be treated as text.

I would convert all the data to a table and not fill any more rows than you have data for. All formulae will fill as you add more rows.