Please disregard this post. Unsure of how to delete it.
I have since resolved this.
The issue was due to the posts being created by Gravity Forms – Post Creation and the custom field was still being assigned a value. After the field was removed from Gravity Forms Post Creation it no longer uses it in the database for Post Type A.
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users