After all of this, I don’t know. There must be something in the append action that has changes since E posted that solution. I’m going around in circles looking at the JS code. You might want to try to contact the regular support and see if they can help. https://www.advancedcustomfields.com/contact/
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users