The mysterious deletion of comments

All new "Disqus" comments, written in Russian (Cyrillic), were erased. Why?
P. S. Comment, written in Japanese, was also removed.

Two weeks passed. Still no answer. The mystery becomes more mysterious.

Now I feel like the protagonist of Kafka's "Das Schloss".

I just checked, and some russian comments are marked as spam by disqus. Especially when posted as "guest comments" (without user account) or when the user has very negative reputation (lots of downvotes and/or marked as spam).

This also happens to english posts, but since dont speak russian in can not tell if the comments are spam or not.