<input type="number" name="listing_price" id="listing-price" value="<?php if ( ! empty ( $cns_stored_meta['listing_price'] ) ) { echo esc_attr( $cns_store_meta['listing_price'][0] ); } ?>"/>
You forget to put “d” where you echo your listing price.
You also not write code for listing_description for save listing editor content.
if( isset( $_POST['listing_description'] ) ) {
update_post_meta( $post_id, 'listing_description', sanitize_text_field( $_POST[ 'listing_description' ] ) );
}
I hope this will help for you.