fileds showing only after (re)publishing

Hello, I noticed that the fields do not show until I republish existing posts.
I tried to do_shortcode but still nothing (and get double on repushied posts).
I tried another plugin that can show the custom fields but I prefer yours because of the titles of the fields which display well.
I guess that your plugin could crawl the posts and add whatever it has to add in the posts.
Any ideas ?
Thanks for your work.