Why is paste suddenly pasting by value?

[NOTE: See ADDED 2 at the bottom. Despite the post's flair, this problem is not solved.]

I'm running Excel on a Mac. I am copying a formula from one cell into another cell. I've done that a squillion times before, and it has always worked fine.

But about half an hour ago, for no apparent reason, something in the world changed.

  • BEFORE: the pasted-into cell ended up with a copy of the formula from the first cell (with any unachored cell references shifted appropriately of course. As usual.
  • BUT NOW: the pasted-into cell ends up with the value produced by the formula in the first cell. WTF?

I hunted about for a bit and tried a few things (although it's hard to get MacOS-specific instructions), but no joy. I'll note:

  1. I have no Excel add-ins
  2. It happens with any workbook, even a brand new one
  3. I have checked everything under Excel > Preferences and can see nothing untoward
  4. Quitting and restarting Excel doesn't fix it
  5. Shutting down and restarting my Mac doesn't fix it
  6. If I Copy and then do Paste Special > Paste, that works fine
  7. I'm on an Apple Silicon (M1) so that, as far as I can make out, resetting things lke the PRAM or SMC don't apply
  8. My Excel itself is up to date; I have "Automatic Updates:" ON
  9. I'm on the Beta update channel

Of the above, #6 seems most curious in that it suggests something might be wrong with my key bindings. (But if so, I can't think of anything I've done to make that happen.)

And so now I want to chuck my Mac out the window, or jump out myself, or even do both at the same time. So, any ideas?

Kit:

  • Computer: MacBook Air, M1 2020
  • OS: MacOS Sequoia 15.2
  • App: Microsoft Excel for Mac Version 16.95 (25012914)
  • Human: Fed up and ready to slap someone

ADDED 1: A new weirdness has arisen. I noticed that if use the Windows Copy and Paste key sequences instead of the Mac ones -- i.e. Ctl-c and Ctrl-v instead of ⌘-c and ⌘-v -- then everything is fine again. But it has to be both of them. In other words:

  • ⌘-c and ⌘-v is broken; i.e. it pastes a copied formula as a value, and
  • ⌘-c and Ctrl-v is broken, and
  • Ctrl-c and ⌘-v is broken, but
  • Ctrl-c and Ctrl-v works; i.e. it pastes a copied formula as a formula

ADDED 2: Notwithstanding the post flair, while it did indeed seem that the problem had been solved, it re-emerged two days later. I've described that in another post but for my part, I'm giving up on trying to fix this. So this is just for the benefit of anyone else who sees the same issue and is looking for clues for a solution