Date format not being accepted [Closed]

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Tuesday August 29, 2017
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August 29, 2017
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I have 2 date columns but no matter what I do they are not being acknowledged as being dates. I opened the same file on my laptop and had no problem with the date format.

example
08/23/2017 22:15:00

I have tried a custom paste special multiply by 1 to remove any spaces and I have tried going through the text to column steps to remove any hidden breaks. Only hint I have is if I try =DATEVALUE(08/23/2017 22:15:00) the 22:15 are hi-lighted in blue.

I just did newest excel update Version 15.37 (170815) why dies this file work fine on laptop and not on my desktop?