Go to Settings > Hotkeys, select one of the available actions and try to assign a hotkey. The field remains empty instead of containing the hotkeys you just tried to assign.
You are probably using wayland. It doesn't work in wayland because how wayland handles key event. It will work in X11. There is a workaround for wayland though. Here is the link Web socket plugin is available on flatpak. install that.
Go to Settings > Hotkeys, select one of the available actions and try to assign a hotkey. The field remains empty instead of containing the hotkeys you just tried to assign.