I just got a respond from acf
Maybe this will help
Hi there,
Thanks for the follow up.
This is not an ACF issue, it is likely that when the field is created using the AJAX plugin a field reference is not created. This field reference is necessary to format the saved value in the database. I would suggest that you ask the plugin developer to pass the values through the update_field() function so that the references can be correctly created.
https://www.advancedcustomfields.com/resources/update_field/
Thanks,
Kenny