when i edit a field of the type checkbox i get the following warning and default values don’t get saved.
Warning: htmlspecialchars() expects parameter 1 to be string, array given in /wp/wp-includes/formatting.php on line 3192
I am getting the same issue. WP 4.0, ACF Pro 5
It does seem that when I create the Field Group and save the checkbox default settings, the settings are indeed saved. The options and defaults are shown on the page editor as expected. It seems the defaults are not properly loading in the ACF Field Editor and therefore appears empty. If you save any changes to the Field Group, the defaults are lost.
Hope that helps in finding the issue.
The 5.0.8 update fixed this issue. Thanks!
Just in case anybody fins this in the future and is on ACF 4.X, I had the same error message (though on an Options page with a textarea field) and it turned out to be unrelated to my fields at all, but because I had a deleted ACF Field Group in the trash. It was a duplicated and renamed group from an ACF import. Anyway, I emptied the Field Group trash and the error went away and my page fields worked again.
