Background of the issue:
I am developing a site that uses a custom post type which I do not want to mark as translatable due to performance reasons and other effects. I use the filter hook wpml_active_languages on every page to input a custom language switch.
Symptoms:
On the singular page of the custom post type, the wpml_active_languages filter returns an empty array, preventing the display of the language switch. However, the singular page displays in the correct language when linked from a normal page.
Questions:
Why does the wpml_active_languages filter return an empty array on the singular page of the custom post type?
Is there a workaround to get the same data for display of the language switch on the singular page of the custom post type?
While you wait for my colleague to take over the ticket, let me try to help you with the issue quickly.
I am not sure if I understood it correctly, but if you are using it on post type that you have set as Not Translatable, then that is expected, as those posts do not have any language information. Only when set as translatable you would have language information for that post type, default language or translation.
