[Geschlossen] GET versteckter Link 404 (Not Found)

Background of the issue:
I am trying to translate or duplicate products to other languages using WPML. When I attempt to duplicate a product, WPML shows an error. Here is the screenshot of the error: versteckter Link. I also noticed that the language icon on the top panel displays incorrectly, making it impossible to select any language version. I have already tried removing my site key, generating a new one, and re-registering the site in WPML → Support → Registration, but the problem remains. My WordPress and PHP settings can be seen here: versteckter Link.

Symptoms:
Unable to translate or duplicate products. WPML throws an error when duplicating products. The language icon on the top panel displays incorrectly, making it impossible to select any language version. Browser console error: GET versteckter Link 404 (Not Found).

Questions:
What is causing the error when trying to duplicate products?
How can I fix the issue with the language icon displaying incorrectly?