Regarding log off and back in to iCloud – this seems to be standard advice to force iCloud to sync. But have you seen problems with this, especially with iCloud Photos?
Be aware that logging off from iCloud can cause a problem in a certain situation, specifically when a Mac has a large Photos library and when the photos are stored in full resolution on that device. Here is a quote from a post in Allison Sheridan’s blog “Podfeet Podcasts” (link provided below):
…Some problems require logging out of iCloud and back in again to solve, or at the very least turning it off and on again. Maybe Contacts got corrupted. Maybe iCloud Drive isn’t syncing properly. Maybe you just bump the checkbox for iCloud Photo Library in System Preferences. This is when things can go horribly wrong.
…Here’s the problem. On the machine which has the full resolution photos, If that connection to iCloud gets disturbed in any way, the iCloud service will check every single image to see if it’s been synced to and from iCloud. With a normal library, this might cause a check of say 1000 photos or even 5000 photos. But when you’ve got 70,000 photos, this turns into a huge problem.
… With a 70,000 photo library, and a 100Mbps symmetric FiOS Internet connection, this process of checking every single photo takes around 3 weeks. That means I have to leave my computer on and not asleep 24 hours a day, 7 days a week for 3 weeks till it’s done verifying every file.
… during this 3 week period, no new photos come down to the Mac, because it’s busy with this tedious task …
The blog post (link below) fully explains this and provides a workaround involving several steps: check for adequate free disk space, turn off iCloud Photos in the top-level system preferences, create a new empty photos library, select select that as the new system library, and finally go back to top-level system preferences and re-enable iCloud Photos.
This work-around procedure bypasses the one-by-one recheck of the old large Photos Library resident in the local device, and instead forces a fresh download of the Photos Library from iCloud. It’s much faster to download all of the images than to re-check them one by one.
@tjluoma described a similar situation with Dropbox syncing all of the old files vs new download of all of the Dropbox files in this post: https://talk.macpowerusers.com/t/replace-dropbox-app-with-maestral/25701/4?u=arthur. Downloading all of the files is faster than syncing all of the files.
After all of that … is there another way to force an iCloud sync, or to force only portions of iCloud to sync (this case Safari tabs) without completely turning off iCloud?
link to blog post in the Podfeet Podcast: