I upgraded to 5.0.9 and values won’t save. I’m running WP 4.0.
Actually, I installed 5.0.8 and it is still not working.
I added fields to a page. It is pretty much a blank install. The only other plugin is Gravity Forms, but I tried disabling that plugin. I’m getting no errors (I have debug on) and I’m getting no console errors.
Wordpress updates its other fields when I hid the update button, just not custom fields.
I’ve used ACF hundreds of times and never had this problem.
I got it working by adding a new page. The fields will save on the new page, just not the old page. Still not sure why. The page was added before I activated ACF.