Unable to overwrite prefix or namespace for ACF blocks

[imre08]

When I generated a new block called Hero and I tried to overwrite the prefix from acf/ to custom/ for example. Problem was that it still rendered with acf/ prefix in the Gutenberg editor. So all my fields were missing from the block. But, when I cached the block.json using wp acorn acf:cache, then it had the correct prefix. But problem with caching was that I had to add re-insert the block for it to work again. Since it showed that acf/hero block was missing. Same problem goes overwriting the namespace.

public $prefix = 'custom/';