In case a file with the name “wp-content/object-cache.php” exists (which is provided by the quite common “Memcached” plugin “http://wordpress.org/extend/plugins/memcached/”, version 2.0.2), then updating of ACF values will fail (not creation though!).
I was wondering if you could emit a simple pointer to this issue at the top of the ACF management section in the backend (“wp-admin/edit.php?post_type=acf”, which integrates the “create_options” method from each field type). That place would be where you get stuck in case you have an “wp-content/object-cache.php” installed and you could simply tell people:
If you are unable to update ACF values, please try removing or renaming the file “wp-content/object-cache.php” from your installation.
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!