There are several recent posts on this same subject. This OS "upgrade" has some issues. The things that may or may not work are:
- Reboot computer
- Log out of iCloud, then back in
- Delete the Numbers app and re-download it from the App Store.
- Call Apple Support
I added that last one to the list because sometimes none of the first three work and that's about the end of our knowledge here (as far as I know). If you do call Apple Support, please report back with what they said that worked for you. It is so disheartening to have these kinds of problems occurring and little we can do here to help.
I may soon add sledgehammer to the list.