Jenesys

-one option to fix the problem-

I don’t know if it would help but just in case.

1. for http://www.example.com/en/feed/ to get it to display content

in my case, I got same problem above because I have woocommerce and polylang plugin activated and Products option set to translate in Polylang -> Setting -> in

“Activate languages and translations for custom post types”. in Custom post types section

#Another word,

If you have Woocommerce and in Polylang -> Settings -> Custom post types

Products – check box is currently checking.

Unchecked it and see if this fix the problem for you.

—————————–

2. to convert from http://www.example.com/en/feed/ to http://www.example.com/feed/

you can do that by set both following sections

2.1 set English (en) , to be your default language in Polylang -> Settings -> Default language -> select English

2.2 in the same Settings -> URL modifications -> Hide URL language information for default language and checked this box.
This one will remove your -en-
from http://www.example.com/en/feed/ to http://www.example.com/feed/

because now -en- is your default language. You can apply the same thing to any other default languages.

Hope this help.