The function works the way it’s supposed to, like I said, as long as there isn’t any errors. I’m not having any issues with ACF working correctly. I think you’re going down the wrong path by trying to figure out what ACF is doing.
To answer your questions, the load_value() method in each field class does what it needs to do base on the field type. The post object fields for examples returns a post ID, or an array or post IDs if something is saved or it returns flash if nothing is saved. On the other hand the taxonomy field has a lot more work to do. All of the functions in ACF are real function, they all do something.
I’m not sure what you mean by adding tracking to the ajax function. This will only run when the ajax request is made. If the function is never run then I would say that there is a JavaScript error that prevents the request from being made in the first place. This goes back to my first reply.
Have you checked for JavaScript errors? Or php errors during the AJAX request?
