Tried the procedure on a public server.
Same results: Create a course, create a site as subdomain but it is not found
…com’s server IP address could not be found.
The site is listed under …/wp-admin/network/sites.php
From the logs:
[05-May-2020 17:13:26 UTC] WordPress database error Table ‘nationi9_openlab.wp_blogs’ doesn’t exist for query SELECT wp_blogs.blog_id FROM wp_blogs WHERE domain IN ( ‘sitename.com’, ‘sitename.com’ ) AND path = ‘/’ ORDER BY CHAR_LENGTH(domain) DESC LIMIT 1 made by require(‘wp-blog-header.php’), require_once(‘wp-load.php’), require_once(‘wp-config.php’), require_once(‘wp-settings.php’), require(‘wp-includes/ms-settings.php’), ms_load_current_site_and_network, get_site_by_path, get_sites, WP_Site_Query->query, WP_Site_Query->get_sites, WP_Site_Query->get_site_ids