photos on iMac not moving to iCloud
I am trying to backup the photos on my iMac in the photos app to iCloud because I am trading in the iMac. The photos in iCloud match the photos in my phone and on my MacBook air - none of the photos on the iMac are in the cloud drive. Do I need to do anything to kick off the file transfer? I do have photos selected in my iCloud configuration.
iMac 21.5″, macOS 10.15