Unit conversion in Spotlight no longer working after upgrade to Tahoe?

Prior to the Tahoe update, I was able to do unit conversion directly in the Spotlight search field. For example, typing in queries like "5 in to mm" or "15 mph to m/s" would result in the corresponding converted values showing directly in Spotlight.

This was *super* convenient for all sorts of stuff. However, this no longer works.

Googling around, I see suggestions for rebuilding the Spotlight index (done), and going to System Settings -> Spotlight -> Results from Apps to make sure "Calculator" and "Conversions" are enabled. I have Calculator enabled there, but there's no Conversions option, unfortunately.

Does anyone know how to restore this functionality?