I FOUND IT! In the middle of the living room rug. I think it popped off last night when I was bringing in a heavy grocery bag and twisted it off my wrist in a weird way, the bag must have snagged a prong.
Yes, everyone should get their prongs checked regularly so consider this your reminder. I was doing this regularly for the first ten years or so but fell out of the habit.
When we bought it there was an insurance plan but IIRC it required getting the prongs checked annually which I haven’t been doing. I personally wouldn’t use homeowners’ insurance for this but I know some people would.
Thanks for the suggestions, DCUM! ❤️