iCloud Drive says it's syncing Desktop & Documents but it's not ... why?

Solution 1:

Ta Da: Followed Andrew Swift's advice found on another forum. First I confirmed that all other devices had iCloud Drive syncing disabled. Then I checked the CloudDocs folder mentioned below and noticed that it held a couple similar entries but looking through them gave me no insights other than some were dated prior to migration and some were current ... hmm! So, I went to Terminal and typed:

killall bird
cd ~/Library/Application\ Support
rm -rf CloudDocs

and then immediately hit restart. I then double checked my mission critical software was running fine (home automation and weather station reading/posting), checked iCloud Drive in the finder and, lo and behold, I saw the desktop file list updating before my vary eyes. And the status bar at the bottom said it was copying a crapload of files & GB to iCloud. I don't know how long it took but I went to bed after 8 hrs of uploading. Today I verified that iCloud.com and iDevices are all on the same wavelength. Alles ist Gut!