A common source of errors in Excel is "the gap"—a situation where you add new data to the bottom of a list, but your formulas ...
If Excel is not recognizing functions after reboot, change calculation settings, disable Show Formula, run Excel ...
When your spreadsheet has formulas piled on top of formulas, tracking and repairing errors would be agony if it weren’t for Excel’s Precedents and Dependents: cells that are referred to by a formula ...