I just ran in to this problem!
Could not figure out what was causing it but when i remove preview=true from the uri it works again.
My dirty hack is to add the following to functions.php (not sure what else this breaks)
if(isset($_GET['preview'])){
unset($_GET['preview']);
}
I’ve put up a blog post that details this problem and the solution to this a bit more. You can find it here http://olaebbesson.se/do-not-use-this-code#do-not-use-this-code
I managed to do a quick, dirty and ugly fix for now.
In advanced-custom-fields-pro\includes\forms\form-gutenberg.php starting from line 89
switch out the acf.addAction segment for the following:
acf.addAction('prepare', function(){
setTimeout(function(){
$('.editor-post-title').after( $('#acf_after_title-sortables').addClass('wp-block m-auto') );
}
, 1000);
$(document).on('click','.editor-post-publish-button', function(){
if($('#poststuff .postbox-container #acf_after_title-sortables-copy').length){
$('#poststuff .postbox-container #acf_after_title-sortables-copy').html(
$('#acf_after_title-sortables').html()
);
}else{
$('#acf_after_title-sortables').clone().attr('id','acf_after_title-sortables-copy').hide().appendTo($('#poststuff .postbox-container'));
}
});
}, 1);
This reply has been marked as private.