Silly me, of course the answer was not number of fields, but number of post vars…
72 fields just happened to push the post vars count over PHP 5’s default limit of 1000. This issue also crops up with really large menus in WP.
Add a php.ini file to /wp-admin/ and put these settings in there (assuming your host allows php.ini overrides):
max_input_vars = 3000 suhosin.post.max_vars = 3000 suhosin.request.max_vars = 3000
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users
Helping others is a great way to earn karma, gain badges and help ACF development!
© 2022 Advanced Custom Fields.