[Закрытые] Multiple issues

Background of the issue:
I am experiencing issues with my website скрытая ссылка after installing WPML. Our setup is similar to other sites where WPML works without issues.

Symptoms:
Our website generates a lot of 404 errors since we installed WPML. These errors disappear after a while or when reloading several times. Additionally, after updating the original post, the new content doesn't appear in the translation editor, preventing translations from being kept in sync across languages.

Example: скрытая ссылка has new content (e. g. new contact person). The translation скрытая ссылка has very old content. That's not because we did not translate it, but because the new content doesn't even appear in the translation editor.

Questions:
How can I resolve the 404 errors that appear after installing WPML?
Why doesn't the new content appear in the translation editor after updating the original post?