It took me 3 weeks before my documents were all completely uploaded.
At least according to the information in the status field of the finder.
After beginning this here post, I called Apple Support which provided me with excellent service via screen sharing and what not. I think we were on for an hour.
While not finding the reason we did mange to find an undocumented and black-box workaround.
It appears that Time Machine was interfering with the sync or vice versa, the support agent could not tell...
At least while the iCloud upload was stuck the Time Machine was 'trying' to perform a backup but that process NEVER progressed. To we cancelled the current backup after which the upload to iCloud commenced.
While the upload indeed commenced the Status in Finder was stuck. So the Finder was indicating that it still needed to upload a lot of stuff but that stuff was actually already uploaded. So we came to the conclusion that the Finder was getting stuck on its progress and thus was not correctly reflecting the actual upload in its status.
The agent asked me to reboot the Mac which I did to see if that would reset the Finder's status. It did. After the reboot the Finder showed that all files had been uploaded.
The agent was surprised by this and said that he was going to log this a bug.
He also stated something which was new to me and something you can all try....
Given the fact the since I had begun uploading the Documents to iCloud the Time Machine had been stuck on its backup (2 weeks) and cancelling that backup ended up fixing the upload to iCloud, the agent was led to the conclusion that something was interfering. He asked me if the Time Machine was setup via the AirPort Extreme. It was. He asked me whether it was setup via cable or air. It was over air. He asked me to physically pull the power on the Airport Extreme (First shutdown Mac) and plug it back in and let it 'do its thing' for 5 minutes. He told me that during boot the unit would check the hard drive and perform some kind of initialisation. When the green light on the unit goes on again, boot the Mac and see check if stuff gets back to 'normal'...
It did, I have not had a single incident since this... So the problem may well be related to Time Machine setup to backup via the AirPort Extreme via Air (WLAN)...
In the end, I can't know for sure. And not knowing the root of the issue is troublesome as it, in theory, could re-occur any time and I would have to start over..
That being said, the iCloud Document & Desktop sync feature is literally saving me countless hours of copying every week given the fact that I work and develop using 3 different Computers. To me this whole thing wound up being worth the stretch... And given the fact that macOS Sierra is still brand new, I hope and believe that once Apple can collect enough user scenarios when this problem is happening, they can fix it with an incremental.
Thanks to all those who contributed to this post... And don't forget -> Provide the Feedback to Apple when and if you have this problem as it enables them to better understand the nature of the issue and thus ultimately fix it !
