From what I can tell, this stems from your use of get_post_field(), which is reserved for fields found in the posts table of the database (ie: built-in to WordPress, rather than custom fields). For custom fields you should use get_post_meta().
From what I can tell, this stems from your use of get_post_field(), which is reserved for fields found in the posts table of the database (ie: built-in to WordPress, rather than custom fields). For custom fields you should use get_post_meta().