I have a wordpress multisite domain setup (subdirectory setup) and all the domains have been working fine (all end in .com). I've recently added a domain ending in .online. When I visit the media page for this domain only, the wait spinner keeps spinning. When I look at the chrome tools, the console shows an error retrieving the ajax.php file (404 error) in this format [domain-name].online/[domain-name].online/wp-admin/admin-ajax.php. I tried disabling all the plugins and changing the theme to no avail. One difference I notice is that in the listing of sites, all the sites start with https://[domain].com. With this site, it starts with ://[domain].online. Adding the "https" string and clicking save changes doesn't change anything (i.e. it still shows "://..."). Any ideas?
Thanks,
Andrew
[domain-name].online/[domain-name].online/wp-admin/admin-ajax.php
and see if you get a 404 too. If you do, try[domain-name].online/wp-admin/admin-ajax.php
and see if that works. This should give you some debugging clues.