Hi, thanks for reaching out! It seems like the Column type formatting might be taking over here and overriding the mapper that you are using. I believe that if you change the Column type from ‘Date’ to ‘Default’, you will get the behavior that you are looking for.
I had tried that initially however the issue with that is it breaks sorting the column by date. A date column that cannot be sorted by date is not very useful. Note the cell with year 2021 not being sorted properly.