Waiting for author
Overview of the issue
Users of TheGem theme may encounter an issue where the language selector dropdown does not function when placed in the Top Area Menu. This behavior occurs because the theme is designed to display only one menu level (depth) in this specific area, and the JavaScript necessary for dropdown functionality is disabled.
Workaround
To work around this limitation, it is recommended to use the WPML’s List of Languages option, which displays all available languages without requiring a dropdown.
Free fix working please
As it is a restriction added by the author, we recommend you to contact him. Otherwise, you can use the workaround here proposed.