Opus Find problem in cyrillics

Opus Unicode. I have a problem in Opus Find if I try to find a word in cyrillic. For example, it is impossible to find anything within such string: 'Nurlan (Нурлан)'. I think the problem exists for all files containg combination of latin and cyrillic symbols. As for texts with only cyrillic symbols, Opus Find behaviour is even more strange with indifference of using 'case sensitive' checkbox.
Maybe there are special features I have to take into consideration?

I have Cyrillic keyboard layout installed and have gone to cpanel and changed my Regional and Language Options>Advanced and sellected Russian under Language for non-Unicode progams.

Still not.


To clarify, is this about searching for filenames, or for strings within the files themselves?