Hi, @seotaro,
I’m assuming your main domain is for example abc.com and your site/sites are like abc.com/site1, abc.com/site2.
So if your site/sites in the subdirectory appears broken, then check ‘Behaviors’ in your AWS Cloudfront distribution, the ‘Path pattern’ should be set to like these:
*/wp-login.php
*/wp-admin/*
*/wp-content/*
*/wp-includes/*
Default (*)