Problem with Language Determines

Thank you for the plugin. My problem: in Chrome and Firefox does not work the definition of the language through http_accept_language. Labels of all fields in English (though translation RU is specified in settings). And in Safari everything is displayed correctly. I checked the navigator.language in console each browser – and there is the value “RU”. My site is in the same language (Russian), but I can’t write the label of the field in Russian, and specify “Field Name” separately.