Status System Configuration Memory Limit Incorrect?

When I go Woocommerce -> PDF Invoices -> Status and look at the WP memory limit reported in the System Configuration section, it shows only 40 M.

The php.ini memory_limit for the version of PHP I’m using on the server is set to 256M, and in Woocommerce -> Status the WP memory limit is correctly reported as being 256M.

I looked in my wp_config.php, and the memory limit is not changed there. I’ve checked a couple of sites, and found the same discrepancy.

I searched, but couldn’t find any other mention of this. Is this a problem with PDF Invoices’ method of checking the PHP memory_limit, or is there a configuration issue I’m missing?