Numbers app on iPhone not working
Just updated to the latest iOS. Now numbers won’t open any files. Not even templates. Deleted the numbers app and downloaded a fresh one. Still not working.
iPhone XR
Restart your phone-->Restart your iPhone - Apple Support
That has fixed the problem for me, at least temporarily. I've got a case open with Apple Engineering, just waiting for it to happen again to catch diagnostics. It's also happened to me with Catalina on my Mac and on my iPad.