On 8, Microsoft rolled out KB5002914 for Excel, but it apparently has a bug that makes it impossible to copy and paste.
Microsoft confirmed an issue in the latest Windows 11 update that breaks copy and paste in Excel.
Windows Report on MSN
Windows 11 copy paste not working: 8 tested fixes
You can fix Windows 11's copy paste not working by running an SFC scan or clearing clipboard data as outlined in this guide.
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