Error: "The operation cannot complete because of an unknown error [NOKY]" in Illustrator

That is the message I get when I try to scale an object in Illustrator 25.3.1 when I try to scale an object.

Mac OS 11.4.

What is the fix for this? I use Illustrator professionally, and can't afford for it to simply refuse to perform straightforward tasks.

{Renamed by MOD}