I know there are a few posts on saving ACF values on pages. Unfortunately, I just spent several hours debugging this issue, and the PHP settings suggested here didn’t work:
http://www.advancedcustomfields.com/faq/limit-number-fields/
After trying about a billion things, I realized it was my theme. Apparently WordPress can get a bit picky with requirements regarding your theme. In my case, I didn’t have an index.php file in my theme (because I wasn’t using it), but that was causing the pages to (I guess) not register correctly with the correct page type.
Once I added an index.php file to my active theme, all of my fields started updating again.
If you’re debugging an issue with fields not saving, try the php.ini fixes, but also be sure your theme is following the recommended guidelines from WordPress.
