This is potentially one of the several bugs breaking sitemap.xml and affecting indexing by search engines, and therefore SERP ranking.
The error given by WP_DEBUG when opening /sitemapindex.xml is:
Notice: Undefined index: custom_field_key in /home/www-data/earmilk/public/wp-
content/plugins/wordpress-custom-fields-permalink-plugin-master/wordpress-
custom-fields-permalink-plugin.php on line 51
This plugin's bug was fixed in this GitHub issue by the plugin's author and maintainer, but the update is not being applied to Earmilk.com plugin install.
This is potentially one of the several bugs breaking sitemap.xml and affecting indexing by search engines, and therefore SERP ranking.
The error given by WP_DEBUG when opening /sitemapindex.xml is:
This plugin's bug was fixed in this GitHub issue by the plugin's author and maintainer, but the update is not being applied to Earmilk.com plugin install.