The Yoast meta box can get in the way.
Learn how to lower the meta box to the bottom of your page in the WordPress backend.
Here is the snippet to add using the Code Snippets plugin.
function move_yoast_to_bottom() {
return 'low';
}
add_filter( 'wpseo_metabox_prio', 'move_yoast_to_bottom');
I also put together a quick video that goes over how to do this if you need a hand :).