Resolved
Overview of the issue
If you are a developer or advanced user creating a theme, WordPress requires that you specify a text domain directive in your theme’s style.css file. This is a unique identifier that allows WordPress to distinguish between all of the loaded translations.
If you do not specify one, you might encounter issues as WPML falls back to the built-in WordPress functions to obtain the theme domain from that entry.
You can read more about the text domain directive in the WordPress documentation.
Workaround
Add a text domain entry in your theme style.css file.
Example:
/* * Theme Name: My Theme * Author: Theme Author * Text Domain: my-theme */