SmartCrawl WPML sitemaps

Looking for a solution to make SmartCrawl to include the language directories ( /de, /en) created via WPML in the sitemap.

At the moment, the sitemap is only including the pages as:

site.com

site.com/de/page1

site.com/de/page2

site.com/en/page1

etc

It’ isn’t adding the root language URL as:

site.com/de/

site.com/en/

This behaviour is causing issue with Google. Please advise what could be done to correct this, if it’s a bug, would appreciate a quick code snippet, or any hooks/filters to manually add these URLs into the sitemap file.