Hi,
Can you please check it now?
I can conclude the there is definitely a bug within the WPML plugin, with the wpml_permalink filter for sure. It does not work as described whatever in the API. Now I added a code to temporarily “switch” the language to get the correct links. Let’s hope it work, because there is nothing else I can do about this unfortunately. I’m not sure if there are any more “bypasses” I can implement to fix the issue within their hook.