Switch keyboard input language doesn't work

I need to make certain table in LibreOffice Calc but after I changed typing language (Settings -> Region and Language -> Add input source -> Serbian Cyrillic) the behavior is the same as before.

I can't find way to type in Cyrillic even when I change it eighter in the top right corner of my screen or via Super + Space.

In Settings -> Region and Language -> Options I've already tried both options but no progress.