copy paste issue in excel 2016

Dear Microsoft Team,

We have been experiencing a copy-paste issue in Microsoft Excel since 14 October 2026, following the installation of Windows Security Update KB5127648 and Microsoft Excel 2016 Security Update KB5002934.

The issue is specific to Sheet1 in the affected Excel workbook. The observed behavior is as follows:

Copying any cell from Sheet2 and pasting it into Sheet1 works correctly.

Copying any cell from Sheet1 and pasting it into another sheet or even within the same sheet does not work. No action is performed, and no error message is displayed.

Copying content from Sheet1 and pasting it into Notepad works correctly.

Copying text or content from Notepad and pasting it into Sheet1 also works correctly.

Based on these observations, the issue appears to be specific to copying cells from Sheet1 rather than a general clipboard malfunction.

Kindly investigate this issue and advise on a permanent resolution, as it started after the installation of the aforementioned security updates.