I don't know when this might have happened (perhaps after the WPML update). All my posts that were translated to English a long time ago no longer have this translation. After changing from Polish to English in language swicher, all my entries are in Polish again. I had the same situation some time ago. Then I translated everything from scratch into English again.
If the way WPML works is that I have to re-translate all my entries from time to time, then something is very wrong here 🙁
regards,
Grzegorz