I find it very hard to believe that two completely different computers, running two completely different operating systems, on a 'reliable' internet connection are having this problem and it's somehow a widespread bug completely unrelated to you specifically.
It's got to be a configuration issue or something similar. I had a similar problem with ONE Mac having this problem with Photos... but I would have been convinced it was me and not Apple had the problem occurred on all three of my Macs, my iPad and my iPhone.
By the way, in my case it took 3 days to sync/upload a 35GB Photos library... and the Photos app showed little to no progress at any given time. It just eventually showed up as done. Now that was when the feature was first released to the public, so I'm sure Apple's servers were saturated as it was. But the point is that it may just take some time, and you need to be patient.