Image in Flexible Content .. can't get ID

Hi,

I've got an image within a flexible content block and I'm trying to get its ID so I can pass it to a WP function

```
$blocks = $post->acf->flexibleContent('flexible_content_blocks');
foreach($blocks as $block) {
$image = $block->fields->image;
$ID = $image->ID; // fails
wp_get_attachment_image($ID, 'fullsize', '', ['class' => 'foo']);
}
```

currently using
```
"jgrossi/corcel": "2.8",
"corcel/acf": "^1.1.1"
```

(I can't update due to other dependencies currently)

thanks for any advice