Square brackets hotkeys used for Increase/Decrease Diameter don’t work when input language is Russian
If you have default [ and ] keys set for Increase/Decrease Diameter, you have to have English input language set to make these work (at least on Windows).
In Russian these keys on a keyboard occupied with 'х' (Russian 'ha') and 'ъ' (Russian hard sign). Pressing them does not change the diameter.
But these do work in Photoshop, and basically elsewhere... except for Illustrator.