100% zoom is not correct size
100% zoom is not correct size in adobe Illustrator 2020 24.1
Go to Preferences and Uncheck - Display Print Size at 100% Zoom. Restart Illustrator and Voila!
It will work.
Worked for me.
Unfortunately the Illustrator software engineering team seems to be convinced their existing code is correct for all installations and hardware. I have attempted to inform them otherwise via a couple other bug reports like this one but all they can say is that it works correctly (when it can clearly be demonstrated not to work correctly some of the time, depending on the monitor in use)