Here's another workaround that does not require an extra column:

Highlight the column of the data in question. Choose data from the ribbon, then "Text to columns". Choose delimited, then next. Choose the default delimiter, makes no difference, then next. Now, select the DATE radio button and choose your format. Then click finish. Your data has been changed to date format. This, I believe, is the easiest method to work around the QBO export bug for dates.