Microsoft’s latest update for Excel 2016 has caused copy and paste to fail for some users, marking the second consecutive month that an Excel update has led to the same problem. The issue affects workbooks that use conditional formatting and may occur without an error message or other warning.
The bug is linked to update KB5002934, which replaced KB5002665, an earlier update that included a fix for a copy-and-paste issue. The problem is limited to Excel 2016; newer versions of Excel are not affected.
Microsoft has since released a fixed build. Users running Excel version 16.0.5574.1006 or later should no longer encounter the bug. To check the installed version, open File > Account and look under About Excel.
As a workaround, Microsoft recommends using the Paste dropdown on the Home tab and selecting Paste Special. The available options include Formulas, Formulas & Number Formatting, Values, Values & Number Formatting, and Link.
Sources: Windows Central.