Devices submenu greyed out in new iTunes 12.7.4.76
I installed the new iTunes yesterday (v. 12.7.4.76) and now I can't back up my iPhone to my Mac, because no devices are showing up and the "Devices" submenu is greyed out. Is this a new glitch, a deliberate decision by Apple, or is there something I need to fix? It was all fine until yesterday.
Mac mini (Late 2012), OS X El Capitan (10.11.6), Various other Macs old and new