I’m using ACF Pro 5.8.10 on WP 5.4.1.
I have custom fields and basically not using Gutenberg. After hiding it with
add_filter('use_block_editor_for_post', '__return_false', 10);
add_filter('use_block_editor_for_post_type', '__return_false', 10);
and saving, all custom fields are removed. I know that the “remove editor” when creating fields is not working with Gutenberg, is there some workaround?