Zend certified PHP/Magento developer

Converting from xlsx to csv in excel changes date data

I need to convert to csv so that I can plot with R Studio, but when I save as a .csv, the date data changes and I don’t mean the format.

For instance, if the date is 2019-05-02 01:30PM in the original document it will convert to 2005-02-19 01:30PM. Changing the format does not help because obviously the year has changed in the data.

Also, this seems to only occur for the first 12 days of each month…

Any help is much appreciated!