copy paste issue in excel 2016

The directional result is useful: Sheet1 can receive data, but copying from Sheet1 fails inside Excel while text reaches Notepad. That does not establish a general Windows clipboard failure or prove which update caused it. Back up the workbook, then reproduce with a tiny new workbook containing two sheets. Compare copying values only with normal paste, first without and then with conditional formatting. Record the exact Excel build and whether it is MSI or Click-to-Run. Microsoft has documented a conditional-formatting paste regression and a revised Excel 2016 MSI update, but that does not confirm your October symptoms have the same cause. Check the latest applicable fix for your installation type rather than uninstalling security updates indiscriminately. If only the original workbook fails, investigate its rules, add-ins and structure. If the new workbook reproduces it, provide Microsoft with that minimal sample and the installed update list.