This is very weird. I needed to change an article title, so I unpublished the article, changed the title, published it again and the title returned to the original one.
No matter in which language area I change it, after publishing the article again, the title goes back to the original.
Hmm… that is odd. I don’t know that this will make a big difference, but it might be worth checking your PHP error logs and reporting on any errors from there.