Custom checkbox field gets unchecked on drag n drop sort

On a custom post type, I created a custom checkbox field within the Featured Image metabox using admin_post_thumbnail_html, and saved it using save_post. However when I sort one of the items, that field gets unchecked automatically and therefore I have to open the post and recheck the checkbox and save it. (and it doesn’t always fall back into sorted place). Perhaps i need something else in my code which saves the state of that checkbox when i use your drag n drop sorting? I’d like to resolve this so my client can drag n drop without worrying about automatically getting that field unchecked. Thank you. I’ll display the code below:

// Add checkbox to Featured Image metabox for Featured Project
		add_filter( 'admin_post_thumbnail_html', 'add_featured_project_display_settings', 10, 2 );
		function add_featured_project_display_settings( $content, $post_id ) {
			$field_id    = 'featured_project';
			$field_value = esc_attr( get_post_meta( $post_id, $field_id, true ) );
			$field_text  = esc_html__( 'Featured Project?', 'bloomer' );
			$field_state = checked( $field_value, 1, false);

			$field_label = sprintf(
					'<p><label for="%1$s"><input type="checkbox" name="%1$s" id="%1$s" value="%2$s" %3$s> %4$s</label></p>',
					$field_id, $field_value, $field_state, $field_text
			);

			return $content .= $field_label;
		} //
		// Save it
		add_action( 'save_post', 'save_featured_project_display_settings', 10, 3 );
		function save_featured_project_display_settings( $post_id, $post, $update ) {
			$field_id    = 'featured_project';
			$field_value = isset( $_REQUEST[ $field_id ] ) ? 1 : 0;

			update_post_meta( $post_id, $field_id, $field_value );
		} //