So, In the query filter, you should use "meta_type=NUMBER" instead of "meta_type=DATE". This will solve the sorting issues if they appear. Screenshot; Screenshot 2021-04-03 at 16.03.20.png
Regarding the display of the date, you need to check with the Oxygen support team how to format a timestamp into a date string, or you need to use Types shortcodes instead of the "oxygen shortcode".