Is "Touch Mode" enabled? If touch mode is enabled, "connected lines", "polygon" and "cloud" tool will be disabled.
You can toggle touch mode by going to menu View -> Show/Hide -> Toolbar Items -> Touch Mode. You can right-click on the horizontal toolbar to add Touch Mode button to it, to make it easier to toggle touch mode.
You can also go to menu Edit -> Preferences, choose General category and select "Never" for Touch Mode if you don't need it.