I'm using a WordPress without a head with WP-API.
So, I expose the data of your yoast in the API. With something like this:
& # 39; yoast_wpseo_title & # 39; => wpseo_replace_vars (get_post_meta ($ post-> ID, _yoast_wpseo_title #, true), $ post)
I have default SEO titles with extract variables set for each of my article types under Search Lookup -> Content Types.
What is strange is that if the default referencing title above for the message is changed, it seems to register and this function returns me the correct title.
But if the default title is not edited, the above function returns null. Also, if I change the default title, it also returns null.
I do not encounter this problem with classic WordPress sites when standard PHP functions are used to directly display these fields.