Why can't I see my Numbers spreadsheets on my new iPhone?
There isn't much to troubleshoot with iCloud syncing and the iOS version of Numbers. (In the sense that even using Xcode to look at the console logs on the device, the error messages are thin to nonexistent.)

When you enable iCloud on one device it should push all the local documents to iCloud so you don't have to connect to iTunes and manage the files manually.

There are three avenues to make the best progress to resolving this issue:


Try your account on another device to rule out your account needing attention before you call on Apple for help.
Try another account on your device to rule out your device's software or settings (or a very long shot that somehow your hardware could be causing it)
Wait it out or call on Apple to investigate.