Copy and Paste cells data within Excel worksheets not working after Office update.

Issue Description:

• Normal copy and paste within Excel no longer works.
• When I copy cells using Ctrl + C and attempt to paste using Ctrl + V, Excel briefly flickers, but nothing is pasted.
• The copied range remains highlighted with the moving dashed border ("marching ants"), indicating that Excel still considers the cells to be copied.
• There is no error message displayed.
• The issue occurs in both existing workbooks and newly created blank workbooks.
• The issue also occurs when Excel is started in Safe Mode (excel /safe).

What Works:

• Cut (Ctrl+X) and Paste works correctly.
• Paste Special → Values works correctly.
• Paste Special → Formulas and Number Formats works correctly.
• Pasting content copied from external applications (such as websites or SSMS) into Excel works correctly.

Troubleshooting Already Performed:

• Tested in a brand-new workbook.
• Tested in Excel Safe Mode.
• Cleared the clipboard.
• Restarted Excel and Windows.
• Disabled add-ins by testing in Safe Mode.
• Verified the issue is not limited to a specific workbook.

Is there a fix available?