If Microsoft Excel does not recognize dates, then there is something wrong with the formatting. Use any of the methods mentioned here to format cells perfectly.

You can change the date & time format in Google Sheets & Excel Online using this guide. Use different date & time formats in spreadsheets.

For example, Excel will automatically choose the date format for a cell that contains 11/11/19. You can set Excel to display dates in a variety of ways, no matter how you type in the data.