Post Publish Date Missing on some posts

Hello,

Some of my posts have a published date and some don't. Here are examples:

Shows Published date: https://tier2tek.com/best-paying-jobs-in-technology/

No Published date: https://tier2tek.com/success-factors-from-working-with-a-staffing-agency/

I'm sure it's a simple setting. Can someone help?

BTW: I installed "Snippets" plugin and am using this code to display "Published date" and "last updated". I don't know much coding, I just copy/pasted it and it's working.

Code:

add_filter( 'generate_post_date_output', function( $output, $time_string ) {
$time_string = '<time class="entry-date published" datetime="%1$s" itemprop="datePublished">%2$s</time>';

if ( get_the_date() !== get_the_modified_date() ) {
$time_string = '<time class="entry-date published" datetime="%1$s" itemprop="datePublished">Published on: %2$s</time> | <time class="entry-date updated-date" datetime="%3$s" itemprop="dateModified">Last Updated on: %4$s</time>';
}

$time_string = sprintf( $time_string,
esc_attr( get_the_date( 'c' ) ),
esc_html( get_the_date() ),
esc_attr( get_the_modified_date( 'c' ) ),
esc_html( get_the_modified_date() )
);

return sprintf( '<span class="posted-on">%s</span> ',
$time_string
);
}, 10, 2 );