Addition (can’t edit):
If you’re using ACF Blocks, you’ll need this snippet
function fix_post_id_on_preview($null, $post_id) {
if ( is_preview() && $post_id !== 'options' && substr( $null, 0, 6 ) != 'block_' ) {
return get_the_ID();
}
else {
$acf_post_id = isset($post_id->ID) ? $post_id->ID : $post_id;
if (!empty($acf_post_id)) {
return $acf_post_id;
}
else {
return $null;
}
}
}
add_filter( 'acf/pre_load_post_id', 'fix_post_id_on_preview', 10, 2 );