Turned out, that the problem comes from using different keyboard layouts: shortcuts with letters work only in English layout, but not Cyrillic one, so this bug looks like a duplicate of https://bugs.launchpad.net/ubuntu/+bug/992706 .
Turned out, that the problem comes from using different keyboard layouts: shortcuts with letters work only in English layout, but not Cyrillic one, so this bug looks like a duplicate of https:/ /bugs.launchpad .net/ubuntu/ +bug/992706 .