I have 1389 photos on creative cloud. These photos are imported in my Lightroom iPhone and have all completed uploading to the cloud. I can see all the photos in both my iPhone and on the web. I recently started to use Lightroom on my Mac. For 5 days my Mac above my name is showing Syncing 1389 photos. On my Lightrooom Mac Preference page under Lightroom mobile in Sync Activity it should 0 uploading, 0 downloading, 1389 Pending. This status have been like that for 5 days!
Could you please check if the Lightroom CC version on your Mac is the latest CC 2015.10?
Do sign out of Creative Cloud App and sign back in. See Sign in and sign out to activate or deactivate Creative Cloud apps
Let us know if that helps.