I was selecting sections in the aforementioned menu and I guess I deselected them all. So now there’s no menu available. It’s a blank space now and I can only switch between ‘Contact Details’, Agenda, Notes, etc. using keyboard shortcuts (Ctrl + Shift 1, 2, 3 and 4).
Right clicking in the right sidebar doesn’t offer any option to bring back the menu and I haven’t seen nothing in the settings to manage the right sidebar (except to expand, to minimize or to hide it). Am I missing something here?