I used both 3.0.0 and 3.0.0 beta 3 (using currently) versions and both have the same bug.
On my site I use WPML plugin to handle 2 languages.
I have a custom post-type called "class". a-c-f is set to show custom fields for all post-type that equals "class". But it only shows in editor for my default language posts.
If I create new class and select default language it will update custom fields correctly, but if I choose English, the a-c-f block disappears right after publishing the class.
What can be the problem? I checked, all the posts in both languages are under the same post-type.