I’m also seeing this on a 3.9.1 site. If I put a check mark in hide content editor and hide featured image and click update, the checked boxes uncheck themselves.
So I tried telling the ACF fields to show after Title – that didn’t save or work either. However all other custom field settings are saving and working without issue.
This site is a site built with the Roots starter theme. I’m using several plugins in addition to ACF like CF7, BackupBuddy, WordFence and responsive lightbox.
To answer the question above, mine is on a page. I’m telling ACF to show the fields for a certain page.
