Warning: Missing required field “updated”.

Where is it suppose to be and why?

This is just my understanding but I believe it let’s google know when the post was last updated. The date of the post will begin to appear in the excerpts on the search engine. Here are a couple links about it but all the fixes only work with other themes:
https://technotes.khitrenovich.com/fix-missing-required-fields-warnings-rich-snippets-testing-tool/

https://www.ilmigo.com/fix-hfeed-warning-field-set-hatomentry.html
Try running another site with this theme through the tool:
https://www.google.com/webmasters/tools/richsnippets

I’m going more in schema.org markup so there will be no update for this *updated* issue.

in content.php add in 22 line <span class=”updated”> around [entry-published]

my line 22:

<?php echo apply_atomic_shortcode( ‘byline’, ‘<div class=”byline”>’ . __( ‘Publicado por [entry-author] el <span class=”updated”>[entry-published]</span> [entry-comments-link before=” | “] [entry-edit-link before=” | “]’, ‘live-wire’ ) . ‘</div>’ ); ?>

[entry-published] is publish date, not updated date.

rich snippet tool