Technically you dont have to create a page or ROOT to use the format you would like to use /en/ for the default language.
At the moment if you go to WPML->Languages and select the checkbox, you can then save without filling out this information.
In the case that you did attempt to fill it out, I would like to request temporary access (wp-admin and FTP) to your site to test the issue.
(preferably to a test site where the problem has been replicated if possible)
**Before we proceed It is necessary to take FULL BACKUP of your database and your website. Providing us with access, you agree that a backup has been taken **
I often use the Duplicator plugin for this purpose: http://wordpress.org/plugins/duplicator/
You will find the needed fields for this below the comment area when you log in to leave your next reply.
The information you enter is private which means only you and I have access to it.
NOTE: If access to the live site is not possible and the staging site does not exist please provide me with a duplicator package created with the duplicator plugin.