iCloud sync is not happening for numbers

Please give us more information!

What devices do you use and what macOS / iOS versions are you running on these devices.

Please create a new Numbers file on each of these devices and check if it is uploaded to iCloud.

Open iCloud directly: https://www.icloud.com/ Under Numbers you should see all files.

Then you can see if a device will upload the file to iCloud, then the issue is most likely on the other device.

Ralf