Craft 3 with Multi-Site: how to not set a primary site, or add a first segment to all primary site URLs?
It looks like you forgot to setup siteUrl in config/general.php for your sites.

'siteUrl' =&gt; [
    'landing' =&gt; 'https://www.mycompany.com/international',
    'sales-en' =&gt; 'https://www.mycompany.com/sales/en',
    'sales-fr' =&gt; 'https://www.mycompany.com/sales/fr',
    ...
],