iCloud & iCloud Photos · Troubleshooting iCloud space
How do I check whether iCloud itself is having problems?
Short answer: Check Apple's System Status page, which shows whether iCloud Drive, Photos, Mail and other services are working. If one is down, syncing resumes by itself once Apple fixes it; if all is well, check your storage, sign-in and connection.
Check Apple's System Status page, which shows whether iCloud Drive, iCloud Photos, Mail and other services are working normally or having an issue. If a service is down, there's nothing to fix on your Mac — syncing resumes on its own once Apple resolves it.
If everything is green, look at your own setup instead: iCloud storage, sign-in and connection. See iCloud files not appearing on other devices.