Iframe disappears when author updates page

If a user has an author role and is listed as the author of a page, when they make changes to the page and click update, the changes are made but the iframe that was in the wysiwyg disappears and no longer shows on the back-end or front-end. If an administrator or editor makes the changes and saves it, the iframe stays.

Besides changing the user role to editor, how do I prevent the iframe from disappearing?

I tried having the author paste the iframe code into the text view and update it while still in text view on the wysiwyg.

I tried adding these coding snippets into the functions file in hopes that it would prevent wp from stripping it, but they're a no-go.

This:

function custom_rewrite_basic() {
   add_rewrite_rule('^about-us/careers/([\w\d-]+)/?', 'index.php? 
   post_type=jobsname=$matches[1]', 'top');
}
add_action('init', 'custom_rewrite_basic');

function add_iframe($initArray) {
    $initArray['extended_valid_elements'] = "iframe[id|class|title|style|align|frameborder|height|longdesc|marginheight|marginwidth|name|scrolling|src|width]";
    return $initArray;
}

// this function alters the way the WordPress editor filters your code
add_filter('tiny_mce_before_init', 'add_iframe');

And this:

function km_add_unfiltered_html_capability_to_editors( $caps, $cap, $user_id ) {
    if ( 'unfiltered_html' === $cap  user_can( $user_id, 'editor' ) ) {
        $caps = array( 'unfiltered_html' );
    }
    return $caps;
}
add_filter( 'map_meta_cap', 'km_add_unfiltered_html_capability_to_editors', 1, 3 );