Why do I have to hit enter for format to work?

Okay so I remember having this question back in college, but never actually had the interest to google this question.

So I have the following data (non-table), And in order for the Date format to work, I have to click the cell, and then hit enter individually for each cell. Is there a way around this? I have the Workbook Calculation set on Automatic.

The E column is a simple concatenate function, from which I then copy the entire column and then paste it as value. Which results in the column F, but as you can see it is not date formated, I have to click the cell and then its formula bar and hit enter for it to work.

Before Clicking Enter

After Clicking Enter