I just had the same issue. It was to do something with the ordering of WordPress meta boxes.
I was recommended by the support team to create a second user account and test with that account. If you can view AFC fields normally in the editor window with the new user account, it is to do with the settings with the old account.
It involves deleting some entries from database entries using phpMyAdmin interface. The recommended I to refer to this article:
https://www.vntweb.co.uk/reset-wordpress-metabox-positions/
It resolved my issue after carefully following the above article.
Best of luck!