Ability to "undo" is removed whenever the sheet saves

Pestomania

Whenever the sheet saves (automatically or otherwise), all ability to undo is taken away. This causes problems when you are troubleshooting a formula and you cannot undo to a time when it worked properly.

NeilKY

I agree with this. It seems a simple enough change to make.

Even better would be to also add a "Version History", similar to google sheets.