Cristi_87 on "[Plugin: WordPress SEO by Yoast] Importing into Yoast Meta fields"

Try to put "_" in front of the meta_keys. I've searched the rows the plugin added in db and it worked for me this way.

update_post_meta($postID, '_yoast_wpseo_focuskw', cleanACII($value->column[2]));

and
update_post_meta($postID, '_yoast_wpseo_metadesc', cleanACII($value->column[3]));