P: Liquify doesn't work with selection

If I make a rectangular selection of an area I'd like to focus on and try to use Liquify tool on that selection, the Liquify window opens, but no matter what brush I use, it won't make any change.

This behaviour is specific only for CMYK images, for RGB images everything works fine.

I tested Photoshop CC 2015, 2017, 2018 and 2019 on Sierra, High Sierra and Mojave. In Sierra everything works as it should, but in High Sierra and Mojave it doesn't.