Just bought the UR22mkIl, installed it with latest update 9.5.21, connected to my iMac, running Sierra 10.12.6. Unable to shut down the iMac with the UR22mkII connected - instead the computer shows an error, then starts back up again. WTF?
Are you using the latest Yamaha Steinberg USB Driver?
Thanks - the latest driver worked (at least for now).