help to format fiscal period in excel output

In RTF template I added column to show fiscal period but the excel output is converting to text.

The xml has tag showing as :

         <START_DATE>2018-01-01T00:00:00.000-05:00</START_DATE>

         <FISCAL_PERIOD>JAN-18</FISCAL_PERIOD>

whereas the excel output is formatting and showing : 

18-Jan

I have tried using below formatting in the item but nothing helps.

<?xdofx:to_char(START_DATE,'MON-YY')?>

<fo:bidi-override direction="ltr" unicode-bidi="bidi-override"><?FISCAL_PERIOD?></fo:bidi-override>

<?format-date:START_DATE;'MMM-YY'?>

I would like the fiscal period column output in excel to show as JAN-18