Fields registered with PHP from within the functions.php file are not not visible in the admin backend. I understand it may be confusing to be able to edit them, but the backend could at least show an overview of the fields added via code.
ACF does not show field groups registered in php in the ACF admin and this is not likely to happen in the future.
https://www.advancedcustomfields.com/contact/
Okay! Thank you for your prompt response.