Multilanguage site with url Path Prefix Language Detection does not recognise path prefix

Issue Summary

I'm using path prefix' to detect site language.
Example:
www.example.com/en
www.example.com/fr

When using subdomain (tested with term-based subdomain), it redirects the term "foo" to foo.example.com/en, which is the expected behaviour, but an error on this page is thrown:
Page not found
The requested page "/en" could not be found.

If I manually try to go to foo.example.com, it'll work, but I lost my language path prefix selector.