post_content not working for custom post

Hi guys

I’m trying to display some columns from a custom post…

These two work fine, giving me the title and url of the custom post:

$title_array[$counter] = $single_result->post_title;
$url_array[$counter] = get_permalink($single_result->ID);

However, the below returns nothing (there is definitely content in the post):

$system_size_array[$counter] = $single_result->post_content

Any ideas how I can get this to work?