KB5002914/KB5002665 — Conditional Formatting on a worksheet breaks Copy/Paste (all forms), Format Painter, and Move-or-Copy Sheet; Microsoft's documented Paste Special workaround does not resolve it

Build affected: Office LTSC 2024, Version 2408, Build 16.0.17932.20996 (also seen on 20976). Still present after KB5002665 (9/16/2026).

Trigger: Presence of any Conditional Formatting rule anywhere on a worksheet — not limited to the specific range being copied. All cells on that sheet are affected, including cells with no CF relationship and no formulas involved. Confirmed to be purely CF-related (not formula-related — initial suspicion of a separate formula-copy bug did not hold up under isolated testing).

Symptoms observed (all on the same trigger):

1. Format Painter — selecting a source range and clicking a destination applies no formatting; the marching-ants selection becomes stuck and cannot be cancelled with Escape or by clicking elsewhere.
2. Paste Special — all sub-options fail, including the workaround options Microsoft specifically documents in KB5002665 (Formulas, Values, Values & Number Formatting, Link). None of them succeed.
3. Move or Copy Sheet (right-click tab → Move/Copy → Create a copy) — fails outright with the generic dialog "We couldn't copy this sheet."

Confirmed workaround / recovery steps:

• Delete all Conditional Formatting rules from the worksheet.
• Save, close, and reopen the workbook (deleting the rules alone is not sufficient — the broken state persists in memory until the file is reloaded).
• After reopening, copy/paste, Format Painter, and Move/Copy Sheet all function normally.
• Re-adding a Conditional Formatting rule immediately reintroduces the bug — no save/reopen needed to break it again, confirming this is a live, real-time trigger tied to CF's presence rather than one-time file corruption.

Relevance to KB5002665: Microsoft's own known-issues text for the 9/16 follow-up update states "If the workbook contains conditional formatting, paste operations might continue to fail," which matches this trigger — but this report shows the scope goes further than "paste operations": Format Painter and whole-sheet copy are also broken, the trigger is worksheet-wide rather than range-specific, and Microsoft's own suggested Paste Special workaround does not mitigate it.