Hi
Sorry not the answer you want but I have just upgraded a Russian site of mine with no problems.
Having seen your post I added a bit more text Мы подбираем для Вас лучших англоговорящих нянь (not sure what that means by the way) with no problems at all.

I was also able to edit and save and even change page titles with no problem.

Do you have any english sections in your site or have you tried any english text to see if that works?

Thanks for your reply,

Yes all Western alphabet languages are working fine, just noticed the same issue is happening with the Japanese language.

Odd that this was working fine in earlier versions.