After ACF-PRO update from version 5.8.1 the className
property has gone from $block array. It doesn’t exist anymore.
function acf_render_block_some_block($block) {
var_dump($block['className']); // this is null, a PHP warning arises
}
Here are the versions of the software:
ACF-PRO: v.5.8.2 (latest)
WP: v.5.2.2 (latest)