Are the dates in your source range real dates or text looking like dates? To check this use the ISNUMBER function on the cells containing " dates" or check if the data is left or right aligned ( if no custom alignment is applied)
If they are left aligned it's text
Also check if you don't have date AND time ( perhaps you used the NOW() function somewhere)?

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Using O365 v2503 - Did you know you can thank someone who helped you? Click on the tiny scale in the right upper hand corner of your helper's post