Thanks for the reply - I’ve followed much of your advice in here over the years! I’ve done all the standard things I can think of - reinstall and reboot, logged in and out. Just checked again and no change - tasks pane works fine in iPhone and IPad apps, but not using Mac desktop or web version. All my apps are the latest versions. Very peculiar. Everything else appears to be working exactly as it should.
Despite being a subscriber for years, I’m struggling to find a way to log a tech support call.