macOS Settings – Fix ‘Show Keyboard & Character Viewers in Menu Bar’ Not Remembered

I see no keyboard & character indicator on the menubar panel, and trying to enable "Show Keyboard & Character Viewers in menu bar" in System Preferences > Keyboard > Keyboard tab, that has no effect and, after closing and re-opening that settings window, Show Keyboard & Character Viewers in menu bar is still NOT ticked.

I use more than one keyboard layout and I need to permanently see the active one on the panel, and switch between them from there (at the present I can only switch from shortcut), like in this image I found on the internet: